DUSHANBE, September 12, 2011, Asia-Plus -- The 10th anniversary of the attacks marked the first time the Democratic and Republican presidents have appeared together publicly since January 2010. But, joined by their wives, the two men made a show of solidarity at Ground Zero in New York, walking in tandem along a memorial pool at the site of the north tower of the World Trade Center.

They nodded their heads during a moment of silence, the only sound the roaring of the waterfall in the pool.

Afterward, they appeared together behind bullet-proof glass near where the names of those killed on September 11 were read aloud.

The crowd at Ground Zero was somber as survivors of the nearly 3,000 killed at the World Trade Center waved photos of lost loved ones.

At Shanksville, Pennsylvania, where Obama continued the commemoration, the mood was more upbeat. Obama and his wife Michelle were greeted with cheers and shouts of "USA, USA" in a grassy field where a memorial is being constructed for the passengers and crew of United 93.

Afterward, the Obamas took a solemn stroll down a trail lined with wildflowers to a large boulder that marked the point of impact for the airliner, which was brought down after a passenger rebellion against the hijackers.

In one of the major successes of his presidency, Obama ordered the secret mission in May that led to the death of al Qaeda leader Osama bin Laden.

But neither the death of the man behind the September 11 hijackings nor the decade-old war in Afghanistan to dislodge the Taliban and defeat al Qaeda played a central role in Obama''s day. Instead, it was filled with remembering those killed in the attacks, and looking ahead to renewal, a theme that was expected to emerge from his evening remarks at a Kennedy Center memorial event in Washington.

At the Pentagon, Obama placed a wreath of white flowers on a stand at the "date line" of the memorial outside the vast building, which says "September 11, 2001 9:37 AM" to mark the time the plane struck.

He then paused and bowed his head in a moment of silence before he and his wife went to greet and take pictures with victims'' family members. The small crowd cheered when the Obamas first arrived, but the president maintained a serious expression for the somber wreath-laying ceremony. A military band played in the background.