Top U.S. military officials told Congress Thursday that they are readying contingency plans for possible conflict in Syria, but remain wary of military intervention.

Defense Secretary Leon Panetta and Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, acknowledged a deteriorating situation in Syria, where President Bashar al-Assad's determination to crush a popular uprising has caused a worsening spiral of bloodshed. Panetta expressed confidence that Assad will be taken down and said the U.S. military was prepared to play a role.

But while Panetta said the United States must keep all options on the table, he warned that it was important to recognize the limitations of military force. He said that America would look to the international community before acting, and cautioned against committing troops to combat.

A decision is that we will not have any boots on the ground and that we will not act unilaterally in that part of the world, Panetta said in testimony to the House Armed Services Committee, adding that the only way that the United States would get involved militarily is if there's a consensus in the international community to try to do something along those lines.

Democrats and Republicans shared Panetta's reservations about military action and questioned him about the precedent set in Libya, where President Barack Obama committed the U.S. military to support air strikes against dictator Moammar Gadhafi despite criticism that he had circumvented Congress. Panetta assured lawmakers that any action would require proper legal authority, noting that the Libya experience had informed how officials were approaching Syria.

Diplomatic efforts to halt the conflict in Syria have been fruitless so far, with violence persisting despite a ceasefire brokered by United Nations special envoy Kofi Annan. The United States has pledged humanitarian assistance and has worked to send communications equipment to Syrian rebels, but has stopped short of sending military gear.

I am not recommending U.S. military intervention, particularly in light of our grave budget situation, unless the national security threat was clear and present, Rep. Howard Buck McKeon, R-Calif., the committee's chairman, said at the hearing. Nevertheless, these reflections lead me to wonder what the United States can do to stem the violence and hasten President Assad from power.

A vocal minority of lawmakers, led by Sen. John McCain, R-Ariz., have called for a more aggressive United States role, including arming the Syrian rebels and launching air strikes. 

It is time for the Obama administration to acknowledge what is obvious and indisputable in Syria: the Annan Plan has failed. Bashar al-Assad has not abided, and will not abide, by a ceasefire, McCain said in a joint statement with independent Sen. Joe Lieberman of Connecticut and fellow Republican Sen. Lindsey Graham of South Carolina. And the only way to stop Assad's campaign of slaughter is for the United States to take tangible steps with our friends and allies to help the Syrian opposition change the military balance of power on the ground.