But Congress, he added, should not take the threat of military action off the table.
Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov planned to meet Thursday in Geneva to try to hash out a possible U.N. plan for seizing control of and potentially destroying Syrias large stockpile of chemical weapons.
Obama appeared to make an indirect reference to the high-stakes chess game over Syria in his remarks at the Pentagon.
Let us have the wisdom to know that while force is at times necessary, force alone cannot build the world we seek, he said.
Hagel also made an apparent reference to Syria in a brief speech later in the day to Pentagon employees.
If theres one clear message we can take away (from 9/11), it is that we must be vigilant, we must always stay ahead of emerging challenges and threats, and we must take action but wise action, wise action when necessary to defend our interests and our country, Hagel said.
Some lawmakers lamented the prolonged period of bitter partisanship that has followed the early sense of shared purpose over the 2001 attacks.
Americans came together as one in the face of something incomprehensible, said Sen. Bill Nelson, D-Fla. We were there for each other in ways big and small, helping one another get through what was a very trying time. To truly honor those we remember today, lets recommit ourselves to embodying that unified spirit.
While Democratic and Republican politicians played tit for tat, an anti-immigration group used the Sept. 11 anniversary to lambast lawmakers from both parties for failing to implement a biometric visa-tracking system.
Noting that several of the (9/11) hijackers had overstayed their visas, the Washington-based Federation for American Immigration Reform said Congress and Obama have ignored a key clause in the Patriot Act, the anti-terror law enacted six weeks after Sept. 11. The clause would require most visa holders to undergo biometric identification, such as fingerprints and retina scans.
Twelve years later, the government could not be farther from implementing the biometric entry-exit system, and Congress refuses to act, the group said.
For all the sparring, some lawmakers tried to steer clear of partisanship for at least a day.
Like all Americans, I will never forget where I was 12 years ago and the way our nation responded in the face of tragedy, said Sen. Patty Murray, D-Wash. On that day, no matter our differences, our region, our race, religion or political party, we were all one thing Americans.
Though the attacks were horrific, they also helped to remind us of what makes our country great and give us hope that our best days are still to come, said Sen. Tim Scott, R-S.C.
The world has changed drastically since that day, but our country remains stronger than ever, said Sen. Mark Begich, D-Alaska.
Soldiers at Arlington Cemetery on 9/11