Remembering 9/11

MLADEN ANTONOV/AFP/Getty Images

US pop singer and song writer Paul Simon performs during the ceremony marking the 10th anniversary of the 9/11 terrorist attacks on the World Trade Center in New York on September 11, 2011. Al-Qaeda hijackers crashed passenger planes into the World Trade Center in New York and the Pentagon in Washington, while a fourth jet crashed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Obama Marks 10th Anniversary Of 9/11 Attacks At The Flight 93 National Memorial

Photo by Jeff Swensen/Getty Images

SHANKSVILLE, PA - SEPTEMBER 11: Visitors walk along the Wall of Names prior to the ceremony marking the 10th anniversary of the crash of United Flight 93 at the Flight 93 National Memorial on September 11, 2011 in Shanksville, Pennsylvania. An estimated crowd of 5,000 watched as the memorial wall was unveiled with the names of the 40 passengers who died when the plane crashed during the terrorist attacks on September 11, 2001.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Spencer Platt/Getty Images

NEW YORK, NY - SEPTEMBER 11: British police march through lower Manhattan beside the World Trade Centersite on the morning of September 11, 2001 in New York City. New York City and the nation are commemorating the 10th anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people when two hijacked planes crashed into the World Trade Center. Security has been heightened in both New York City and Washington D.C. following a terrorist threat relating to a car bomb.

US President Barack Obama and First Lady

MANDEL NGAN/AFP/Getty Images

US President Barack Obama and First Lady Michelle Obama arrive for a commemoration ceremony at the Flight 93 National Memorial on the 10th anniversary of the 9/11 attacks in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Family members read names of victims at the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Fire Fighters Commemorate 10th Anniversary Of Sept. 11th Attacks

Photo by Mario Tama/Getty Images

NEW YORK, NY - SEPTEMBER 11: Martin County, Florida Fire Rescue firefighter Sean McCallister (L) holds his daughter Caitlyn while wife Julia (R) holds their son Sean at a memorial service for firefighters killed on 9/11 at the Firemen's Monument at Riverside Park on Septemnber 11, 2011 in New York City. Firefighters from around the world have converged on New York to take part in the anniversary services. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: For Mayor of New York Rudy Giuliani speaks at the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Anniversary of Sept. 11th Attacks Marked At Pentagon

Photographer: Joshua Roberts/SIPA

U.S. President Barack Obama and First Lady Michelle Obama lay a wreath on the during a remembrance ceremony at the Pentagon in Washington, DC, on Sunday, Sept. 11, 2011.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Familes of victims attend the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Remembering 9/11

MLADEN ANTONOV/AFP/Getty Images

US President Barack Obama addresses the relatives at the 9/11 memorial in New York, September 11, 2011, during the official ceremony marking the 10th anniversary of the terrorist attack. In the September 11, 2001 attacks, Al-Qaeda hijackers crashed passenger planes into the World Trade Center in New York and the Pentagon in Washington, while a fourth jet crashed in Shanksville.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Allan Tannenbaum-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: (L-R) Laura Bush, former President George Bush, First Lady Michelle Obama, and President Barack Obama salute at the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Anniversary of Sept. 11th Attacks Marked At Pentagon

Photographer: Joshua Roberts/SIPA

U.S. President Barack Obama and First Lady Michelle Obama lay a wreath on the during a remembrance ceremony at the Pentagon in Washington, DC, on Sunday, Sept. 11, 2011.

Remembering 9/11

MLADEN ANTONOV/AFP/Getty Images

US President Barack Obama addresses the relatives at the 9/11 memorial in New York, September 11, 2011, during the official ceremony marking the 10th anniversary of the terrorist attack. In the September 11, 2001 attacks, Al-Qaeda hijackers crashed passenger planes into the World Trade Center in New York and the Pentagon in Washington, while a fourth jet crashed in Shanksville. AFP PHOTO / Mladen ANTONOV (Photo credit should read MLADEN ANTONOV/AFP/Getty Images)

Anniversary of Sept. 11th Attacks Marked At Pentagon

Photographer: Joshua Roberts/SIPA

U.S. President Barack Obama and First Lady Michelle Obama lay a wreath on the during a remembrance ceremony at the Pentagon in Washington, DC, on Sunday, Sept. 11, 2011.

Anniversary of Sept. 11th Attacks Marked At Pentagon

Photo by Joshua Roberts-Pool/Getty Images

U.S. President Barack Obama and First Lady Michelle Obama lay a wreath on the during a remembrance ceremony at the Pentagon in Washington, DC, on Sunday, Sept. 11, 2011. Photographer: Joshua Roberts/SIPA

Anniversary of Sept. 11th Attacks Marked At Pentagon

Photo by Joshua Roberts-Pool/Getty Images

U.S. President Barack Obama and First Lady Michelle Obama lay a wreath on the during a remembrance ceremony at the Pentagon in Washington, DC, on Sunday, Sept. 11, 2011. Photographer: Joshua Roberts/SIPA

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

NEW YORK, NY - SEPTEMBER 11: The North Pool of the 9/11 Memorial, with One World Trade Center under construction at rear during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. (Photo by Robert Deutsch-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

NEW YORK, NY - SEPTEMBER 11: New York City Police Officer Danny Shea, a military vet, salutes at the North pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. (Photo by David Handschuh-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

NEW YORK, NY - SEPTEMBER 11: Security personel keep watch during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. (Photo by Robert Deutsch-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

New York police and firefighters and Port Authority Police line up at one of the entrances of 9/11 Memorial Plaza before the tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/Chip Somodevilla/Getty Images

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

New York police and firefighters and Port Authority Police line up at one of the entrances of 9/11 Memorial Plaza before the tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/Chip Somodevilla/Getty Images

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

NEW YORK, NY - SEPTEMBER 11: U.S. President Barack Obama (R), first lady Michelle Obama (2nd R), former President George W. Bush (2L) and former first lady Laura Bush look out at the North Pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. (Photo by Robert Deutsch-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

<> on September 11, 2011 in New York City.

Remembering September 11

NEW YORK, NY - SEPTEMBER 11: Robert Peraza, who lost his son Robert David Peraza, pauses at his son's name at the North Pool of the 9/11 Memorial during tenth anniversary ceremonies at the site of the World Trade Center on September 11, 2011, in New York City. New York City and the nation are preparing to commemorate the 10th anniversary of the 9/11 terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. Security has been heightened in both New York City and Washington D.C. following a possible car bomb threat. (Photo by Justin Lane-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

NEW YORK, NY - SEPTEMBER 11: Bagpipers walk past the North Pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. (Photo by Robert Deutsch-Pool/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

at the National September 11 Memorial at the World Trade Center site in New York, Sunday, Sept. 11, 2011. (AP Photo/Seth Wenig, Pool)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

at the National September 11 Memorial at the World Trade Center site in New York, Sunday, Sept. 11, 2011. (AP Photo/Seth Wenig, Pool)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

New York police and firefighters and Port Authority Police line up at one of the entrances of 9/11 Memorial Plaza before the tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/Chip Somodevilla/Getty Images

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Former New York Governor George Pataki and Anthula Katsimatides, who lost her brother on 9.11, cry at the North pool of the 9.11 Memorial during tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/David Handschuh/Daily News

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

11 September 2011-At dawn on September 11, 2011, the Freedom Tower rises over the North Pool at the September 11th Memorial at the World Trade Center site.
Photo Credit: Jefferson Siegel/Sipa Press

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

at the National September 11 Memorial at the World Trade Center site in New York, Sunday, Sept. 11, 2011. (AP Photo/Seth Wenig, Pool)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

<> on September 11, 2011 in New York City.

Remembering September 11

A patch remembering a relative is carried at the 9/11 Memorial on September 11, 2011 in New York as the US marks the 10th Anniversary of the September 11, 2001 attacks. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

Former US President George W. Bush and President Barack Obama visit the 9/11 memorial on September 11, 2011 in New York on the 10th anniversary of the 9/11 attacks. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Robert Peraza found the name of his son, Robert David Peraza who died on 9.11.01 at the North pool of the 9.11 Memorial during tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/David Handschuh/Daily News NEW YORK, NY - SEPTEMBER 11: Police officers stand near and take pictures of a memorial pool at the National September 11 Memorial at the World Trade Center site on September 11, 2011 in New York City. New York City and the nation are preparing to commemorate the 10th anniversary of the 9/11 terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. Security has been heightened in both New York City and Washington D.C. following a possible car bomb threat. (Photo by Seth Wenig-Pool/Getty Images)

Remembering September 11

(L-R) Former US First Lady Laura Bush, former US President George W. Bush and President Barack Obama visit the 9/11 memorial on September 11, 2011 in New York on the 10th anniversary of the 9/11 attacks. AFP PHOTO/Mandel NGAN (Photo credit should read MANDEL NGAN/AFP/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

during tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York. POOL/Todd Heisler/The New York Times

Remembering September 11

People arrive in the early hours of September 11, 2011 before the 10th Anniversary commemoration of the September 11, 2001 attacks at the lower Manhattan site of the World Trade Center in New York. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

Elba Cedeno holds a photograph of her partner Catherine Theresa Smith at the 9/11 Memorial on September 11, 2011 in New York as the US marksthe 10th Anniversary of the September 11, 2001 attacks. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

A man holds a photograph of a relative during the 10th Anniversary commemoration of the September 11, 2001 attacks at the lower Manhattan site of the World Trade Center in New York. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

A person holds up a photograph of relatives at the 9/11 Memorial on September 11, 2011 in New York as the US marksthe 10th Anniversary of the September 11, 2001 attacks. AFP PHOTO/Stan HONDA (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

The sun rises at the site of the 9/11 Memorial on September 11, 2011 in New York as the US marksthe 10th Anniversary of the September 11, 2001 attacks. AFP PHOTO/Stan HONDA during (Photo credit should read STAN HONDA/AFP/Getty Images)

Remembering September 11

People carry portraits of their dead relatives as they gather at the 9/11 memorial in New York, September 11, 2011, during the official ceremony marking the 10th anniversary of the terrorist attacks. In the September 11, 2001 attacks, Al-Qaeda hijackers crashed passenger planes into the World Trade Center in New York and the Pentagon in Washington, while a fourth jet crashed in Shanksville. AFP PHOTO / Mladen ANTONOV (Photo credit should read MLADEN ANTONOV/AFP/Getty Images)

Remembering September 11

US Army, police and fire brigade officers practice with a US flag at the stage at the 9/11 memorial in New York, September 11, 2011, prior to the official ceremony marking the 10th anniversary of the terrorist attack. In the September 11, 2001 attacks, Al-Qaeda hijackers crashed passenger planes into the World Trade Center in New York and the Pentagon in Washington, while a fourth jet crashed in Shanksville. AFP PHOTO / Mladen ANTONOV (Photo credit should read MLADEN ANTONOV/AFP/Getty Images)

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Kristoffer Tripplaar-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: President Barack Obama visits the North Pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City. New York City and the nation are commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Remembering 9/11

Photo credit should read MANDEL NGAN/AFP/Getty Images

US President Barack Obama (L) and First Lady Michelle Obama (2nd L), with former US President George W. Bush (2nd R) and First Lady Laura Bush observe a moment of silence during the commemoration ceremony at the National September 11 Memorial on September 11, 2011 in New York City as the US remembers the 9/11 attacks on the 10th anniversary.

Remembering 9/11

Photo credit should read MANDEL NGAN/AFP/Getty Images

(L-R) Former US First Lady Laura Bush, former US President George W. Bush, First Lady Michelle Obama and President Barack Obama visit the 9/11 memorial on September 11, 2011 in New York on the 10th anniversary of the 9/11 attacks.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Kristoffer Tripplaar-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: U.S. President Barack Obama , first lady Michelle Obama, former President George W. Bush and former first lady Laura Bush look out at the North Pool of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City.

The Annual Tribute In Light Memorial

Photo credit should read STAN HONDA/AFP/Getty Images

The annual Tribute in Light memorial echoing the twin towers of the World Trade Center illuminates the night sky during the 10th Anniversary of the September 11, 2001 attacks at the lower Manhattan site of the World Trade Center September 11, 2011, in this view from Bayonne, New Jersey. The Statue of Liberty is seen at left.

The Annual Tribute In Light Memorial

Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images

The Tribute in Light illuminates the sky in New York September 11, 2011 on the 10th anniversary of the 9/11 attacks. The tribute, an art installation of the Municipal Art Society, consists of 88 searchlights placed next to the site of the World Trade Center creating two vertical columns of light in remembrance of the September 11, 2001 attacks.

Anniversary Of Sept. 11th Attacks Marked At Pentagon

Photo by Win McNamee/Getty Images

ARLINGTON, VA - SEPTEMBER 11: During a remembrance ceremony, U.S. service members prepare to place wreathes on the memorial benches at the Pentagon Memorial September 11, 2011 in Arlington, Virginia. The nation is commemorating the tenth anniversary of the terrorist attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Washington DC Observes 10th Anniversary Of September 11 Attacks

Photo by Mark Wilson/Getty Images

WASHINGTON, DC - SEPTEMBER 11: People carry flags of the U.S. states, and of other countries that had people killed in the 9/11 terrorist attacks, on September 11, 2011 in Washington, DC.

President Obama Attends "Concert For Hope" Commemorating 9/11 Attacks

Photo by Alex Wong/Getty Images

WASHINGTON, DC - SEPTEMBER 11: (R-L) U.S. President Barack Obama, first lady Michelle Obama, Vice President Joseph Biden and his wife Jill Biden attend the "A Concert For Hope" event, hosted by Washington National Cathedral, to mark the tenth anniversary of the 9/11 terrorist attacks September 11, 2011 at the Kennedy Center in Washington, DC.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

POOL/Noah K. Murray/The Star-Ledger

Family members listen to speakers during tenth anniversary ceremonies at the site of the World Trade Center September 11, 2011, in New York.

Anniversary Of Sept. 11th Attacks Marked At Pentagon

Photo by Win McNamee/Getty Images

ARLINGTON, VA - SEPTEMBER 11: Following a remembrance ceremony, family members of those who died in the attack on the Pentagon take family photos as they visit the Pentagon Memorial September 11, 2011 in Arlington, Virginia.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by David Handschuh-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Family members who lost loved ones attend the memorial during tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site September 11, 2011 in New York City.

New York City Commemorates 10th Anniversary Of 9-11 Terror Attacks

Photo by Timothy A. Clary-Pool/Getty Images

NEW YORK, NY - SEPTEMBER 11: Families line up against the wall of the 9/11 Memorial during the tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site, September 11, 2011 in New York City.

President Obama Attends "Concert For Hope" Commemorating 9/11 Attacks

Photo by Alex Wong/Getty Images

WASHINGTON, DC - SEPTEMBER 11: Singer Patti LaBelle performs during the "A Concert For Hope" event, hosted by Washington National Cathedral, to mark the10th anniversary of the 9/11 terrorist attacks September 11, 2011 at the Kennedy Center in Washington, DC.

President Obama Attends "Concert For Hope" Commemorating 9/11 Attacks

Photo by Alex Wong/Getty Images

WASHINGTON, DC - SEPTEMBER 11: Singer-songwriter Alan Jackson performs during the "A Concert For Hope" event, hosted by Washington National Cathedral, to mark the10th anniversary of the 9/11 terrorist attacks September 11, 2011 at the Kennedy Center in Washington, DC.