WASHINGTON - President Barack Obama stepped back from the brink on Saturday and delayed an imminent military strike against Syria to seek approval from the US Congress in a gamble that will test his ability to project American strength abroad and deploy his own power at home.
Before Obama put on the brakes, the path had been cleared for a US assault. Navy ships were in place and awaiting orders to launch missiles, and UN inspectors had left Syria after gathering evidence of a chemical weapons attack that US officials say killed 1,429 people.
But Obama decided to seek the backing of US lawmakers before attacking, as polls showed strong opposition from Americans already weary of wars in Iraq and Afghanistan. Approval will take at least 10 days, if it comes at all.
"Today I'm asking Congress to send a message to the world that we are ready to move as one nation," Obama said in a dramatic shift he announced in the White House Rose Garden.
Obama, whose credibility has been called into question for not punishing the government of Syrian President Bashar al-Assad for earlier poison gas attacks, warned lawmakers they must consider the cost of doing nothing in Syria.
"Here's my question for every member of Congress and every member of the global community: What message will we send if a dictator can gas hundreds of children to death in plain sight and pay no price?" he said.
Obama's approach, which he debated with top aides on Friday night, has left in doubt whether the United States will carry through with the military steps that the president has already approved.
Backing from Congress is by no means assured, with many Democrats and Republicans uneasy about intervening in a distant civil war in which 100,000 people have been killed over the past 2-1/2 years.
Obama's decision to consult with Congress is in line with an argument he has often made for a more collaborative approach to foreign policy in Washington than there was under his predecessor, President George. W. Bush.
But another reason to bring lawmakers into the process is that Obama might be able to share some of the responsibility with Congress if it votes for strikes on Syria that turn badly for Washington.
Lawmakers for the most part welcomed Obama's decision but looked in no hurry to come back to Washington early from their summer recess, which lasts until Sept. 9.
"In consultation with the president, we expect the House to consider a measure the week of September 9," said John Boehner, the top US Republican and speaker of the House of Representatives. "This provides the president time to make his case to Congress and the American people."
House members are to receive a classified briefing on Sunday from administration officials to hear the case against Syria. Officials briefed senators on Saturday. British Prime Minister David Cameron, who was unable to persuade the British parliament to back action earlier in the week, welcomed Obama's decision, as did the government of French President Francois Hollande, with whom Obama spoke on Saturday.
In rebel-held areas of Syria, there was a sense of frustration and disappointment.
"God curse everything," said an activist in the rebel-held territory of Idlib, Ahmad Kaddour. "We've become just a game to people. I think this is going to make the situation worse for those of us living here."
A Reuters reporter visited a group of fighters and activists sitting in a home in Aleppo city. They had not watched Obama's speech, and when told of the president's decision, they all agreed it meant there would be no US strike.
"This is the same old hesitancy that the United States have tortured us with since the beginning of the revolution," one said.DECISION MADE FRIDAY NIGHT
At the White House, Obama's decision surprised senior aides when he informed them of it on Friday night after they had concluded the president already had the legal authority to act on his own.
Officials said he laid out the idea of going to Congress during a 45-minute walk on the White House south grounds with chief of staff Denis McDonough, then debated the risks with others in his inner circle, some of whom argued against his logic.
Senior administration officials who briefed reporters after Obama spoke said they believed Congress will vote in favour of a US military strike because of the threat chemical weapons pose to the security of US ally Israel and other friends in the region.
Jon Alterman, a former State Department official who is a Middle East expert at the Center for Strategic and International Studies, said failure by Obama to get his way "could be something that not only dominates September and October, but could shadow the rest of the administration."
Obama sent draft legislation to Congress on Saturday formally asking for approval to use military force in Syria to"deter, disrupt, prevent and degrade" the potential for further chemical attacks.
The Aug. 21 attack was the deadliest single incident of the Syrian civil war and the world's worst use of chemical arms since Iraq's Saddam Hussein gassed thousands of Kurds in 1988.
The team of UN experts arrived in the Netherlands on Saturday carrying evidence and samples relating to the attack. They had flown from Beirut after crossing the border into Lebanon by road earlier in the day.
The 20-member team had arrived in Damascus three days before the attack to investigate earlier accusations of chemical weapons use. After days holed up in a hotel, they visited the sites several times, taking blood and tissue samples from victims and from soldiers at a government hospital.
War weariness cost Washington the support of its closest ally: Britain has voiced backing for action but was forced to drop any plans for a military strike after Cameron unexpectedly lost a vote over it in parliament on Thursday, straining London's "special relationship" with Washington.
Syria and its main ally, Russia, say rebels carried out the gas attack as a provocation. Moscow has repeatedly used its UN Security Council veto to block action against Syria and says any attack would be illegal and only inflame the civil war there.
"I am convinced that (the chemical attack) is nothing more than a provocation by those who want to drag other countries into the Syrian conflict," Russian President Vladimir Putin said on Saturday.
Syria's Foreign Ministry repeated its denial that the government had used chemical weapons against its own people. Washington says the Syrian denials are not credible and that the rebels would not have been able to launch such an attack.
Syria's neighbour Turkey backs the use of force. The Arab League has said Syria is to blame for the chemical attack but so far stopped short of explicitly endorsing Western military strikes. Arab League foreign ministers are due to meet in Cairo on Sunday.
Iran, Assad's main ally in the region, has condemned plans for strikes and warned of wider war.