By David Alexander
ABOARD A U.S. MILITARY AIRCRAFT (Reuters) - The U.S. military is prepared for any action against Syria that may be necessary, but officials are still focused on more aggressive international pressure to bring about the ouster of President Bashar al-Assad, U.S. Defense Secretary Leon Panetta said on Thursday.
Panetta, speaking to reporters en route to Singapore for a security conference, stopped short of advocating U.S. action without the endorsement of the U.N. Security Council, but said the international community needed to act more aggressively to obtain Assad's ouster while there was time.
"This is an intolerable situation," Panetta said. "We cannot be satisfied with what is going on. And the international community has got to take further steps to make sure that Assad steps down."
Asked about the possibility of U.S. military action without U.N. endorsement, Panetta said "I cannot envision that," adding that it was important to have "the kind of support that we need in order to accomplish the mission."
His remarks came a day after Susan Rice, the U.S. ambassador to the United Nations, suggested military action without U.N. authorization might be necessary if the U.N. Security Council failed to agree on a course to address the Syrian situation.
Asked if he disagreed with Rice's assessment, Panetta said the United States maintained all possible options for future action, but it was "very important right now that we continue to work with the international community because we all share the same goals here."
Russia, a leading ally of Assad, has been resistant to further U.N. action against his government, which is fighting to put down a rebellion that began as part of the Arab Spring protests for greater democratic governance in the region.
Diplomatic efforts to end the bloodshed, including a U.N. brokered peace deal last month, have failed to end the fighting.
Demands for outside action have risen in recent days amid reports of a massacre that killed dozens of children and the killing of 13 people who appeared to have been tied up and shot at close range.
Panetta warned that as the situation in Syria drags on, more and more countries like Iran and others in the region will become involved, making it more difficult to bring about a transition to a stable new government.
"The longer this goes on, I think the greater the threat that the situation is going to get worse in terms of what happens ultimately when Assad does step down," he said.
"I think the key right now, and I think we still have the opportunity, is to make an effective transition, getting rid of Assad, but doing it in a way that continues to provide stability for Syria. That ought to be the goal that we try to achieve."
(Editing by David Brunnstrom)