WASHINGTON — The apparent poison gas attack that killed hundreds of Syrian civilians last week is testing President Obama's views on military intervention, international law and the United Nations as no previous crisis has done.
The former constitutional law professor, who came to office determined to end what critics called the cowboy foreign policy of George W. Bush, now is wrestling with some of the same moral and legal realities that led Bush to invade Iraq without clear U.N. consent in 2003.
As U.S. officials discussed diplomatic and military options with allies in Europe and the Middle East, White House advisors indicated Tuesday that they were unlikely to seek either a vote in Congress or at the U.N. Security Council to authorize use of force. Last week, Obama said he had concerns about launching an attack on Syrian President Bashar Assad's government without a U.N. mandate.
Russia and China would almost certainly veto or delay any U.N. resolution condemning Syria or sanctioning reprisal. Top British and French officials, who are likely to support U.S. military action, have signaled they don't think a detour to the U.N. would be worthwhile.
White House Press Secretary Jay Carney said Tuesday that virtually no one doubted that Assad's government had carried out a chemical attack last week. But the Obama administration has yet to reveal the intelligence that led to that conclusion.
Syria's foreign minister, Walid Moallem, denied that government forces had used chemical weapons. "I dare them to produce any single piece of evidence," he said at a news conference in Damascus, the Syrian capital.
White House officials cautioned that Obama was still considering the options, but the administration appeared positioned to act quickly once he chooses a course. Defense Secretary Chuck Hagel said during a visit to Brunei that the Pentagon was prepared to strike targets in Syria and hinted that such a move could come within days.
Some experts said U.S. warships and submarines in the eastern Mediterranean could fire cruise missiles at Syrian targets as early as Thursday night, beginning a campaign that could last two or three nights. Obama leaves next Tuesday for a four day trip to Sweden and Russia, which strongly supports Assad's government, for the G-20 economic summit.
One U.S. official who has been briefed on the options on Syria said he believed the White House would seek a level of intensity "just muscular enough not to get mocked" but not so devastating that it would prompt a response from Syrian allies Iran and Russia.
"They are looking at what is just enough to mean something, just enough to be more than symbolic," he said.
Obama and his top aides have shared intelligence with key members of Congress. But White House aides made it clear Tuesday that Obama would not wait for Congress to return from its monthlong recess on Sept. 9, and House and Senate leaders signaled no plans to call members back for an emergency session.
"I can't imagine the president is going to do much more than the outreach he's already doing," said Jim Manley, former aide to Sen. Majority Leader Harry Reid (D-Nev.).
Sen. Carl Levin (D-Mich.), chairman of the Senate Armed Services Committee, said after a briefing that the administration was "proceeding cautiously." Obama is "considering a broad range of options that have been presented by our military leaders," he said.
Still, a growing number of lawmakers in both parties pressed the White House to seek authorization from Congress.
Rep. Scott Rigell (R-Va.) collected nearly three dozen signatures of House members on a letter he intended to send to the White House. It states that military action without a congressional vote "would violate the separation of powers that is clearly delineated in the Constitution." Congress stood ready to return for a debate on the issue, the letter says.
Other lawmakers worried that a few days of missile strikes might be counterproductive.
Sen. Christopher S. Murphy (D-Conn.), a member of the Foreign Relations Committee, said it would be "little more than a slap on the wrist" to the Syrian government, but could provoke retaliation from Assad that could draw America into "a much wider and much longer-term conflict that could mean an even greater loss of life within Syria."
Because of safety concerns, the team of U.N. inspectors in Damascus was forced to scrub a planned visit Tuesday to one of the suburbs allegedly hit by poison gas. They are to leave Syria on Sunday, but they probably will be withdrawn earlier if Washington warns that missile strikes are imminent.
"I would doubt" the United States or its allies would attack while the U.N. team was still in Syria, said Jean Pascal Zanders, a Belgian scientist and author of a blog that focuses on chemical weapons issues.