NEW YORK // After withstanding two years of internal and international pressure to intervene in Syria, Washington was finally forced to provide military support to rebels who have suffered several painful defeats in recent weeks.
The White House announced late on Thursday that it had confirmed the Syrian military had used chemical weapons, including sarin gas, against opposition forces seeking to overthrow the government of President Bashar Al Assad. That meant the "red line" set by US President Barack Obama last August had been crossed. But analysts say the role of Hizbollah and Iran in shoring up the regime's armed forces largely contributed to the change in US policy.
"The Assad regime should know that its actions have led us to increase the scope and scale of assistance that we provide to the opposition, including direct support," one of Mr Obama's top advisers, Ben Rhodes said. "These efforts will increase going forward."
For months, the Obama administration has faced down withering criticism by allies in the Arabian Gulf and Europe over its non-intervention policy in the civil war that has killed more than 90,000 Syrians.
Within the White House there have been deep divisions as well, with senior advisers arguing that intervention was a slippery slope that could lead to an Iraq-like quagmire winning the debate over those in the State Department and Pentagon who supported limited military intervention, including a no-fly zone and air strikes on strategic targets.
But the crushing defeat of rebels in the town of Qusayr by the Syrian military, aided by Hizbollah fighters as well as an influx of arms from Russia and Iran, appears to have quickly tilted the debate finally in favour of those arguing for intervention.
"I think the chemical weapons [use] was probably only a very small part of the decision," said David Pollock, a former State Department official and fellow at the Washington Institute of Near East Policy think tank. "The real concern is that the opposition was about to be defeated."
Deep concerns within the administration about what a total defeat of the Syrian opposition would mean for containing Iran, Washington's greatest adversary in the region were also a factor. People in the administration "started to make the argument that our credibility, not just on Syria but on Iran was suffering and was at stake and if we didn't do something more serious we were going to lose it", he said. "That may have been the last straw."
The White House is still clearly cautious and likely considers all of its options in Syria to be bad ones.
Writing in Foreign Policy magazine earlier in the week, before Thursday's announcement, Middle East analyst Aaron David Miller summed up the dilemma: "None of the incremental steps that have been proposed so far have answered the following questions: Can these actions degrade Syria's military power so that President Bashar Al Assad's regime collapses? Or, alternatively, can they produce a stalemate that would force the regime, the Russians, and Iran to accept a negotiated transition?"
Senior administration officials were reported in The New York Times as saying the military aid will consist of light arms, ammunition and perhaps anti-tank weapons. There was no mention of the anti-aircraft missiles the rebels have demanded or air strikes and the idea of an immediate no-fly zone was dismissed by Mr Rhodes.
By providing more guns and bullets but little else, the White House hopes to increase the rebels' military leverage, forcing all sides to the negotiating table at the Geneva 2 peace talks to which Washington and Moscow had tentatively agreed.
"It's almost certainly not enough to reach a settlement," said Mr Pollock. "But it's a step that avoids the worst outcome."
Mr Obama is scheduled to meet Russian President Vladimir Putin on the sidelines of the G8 summit next week where Mr Obama is expected to try to persuade his counterpart to reconsider Russia's substantial military support for Syria.
That eventuality appears unlikely, and the Obama administration's announcement appears to have put it on a collision course with Moscow. In the weeks after the agreement over the Geneva talks, Russian officials have ramped up their public support for the Assad government as well as Iran, which may also have contributed to the Obama administration's announcement.
While the imposition of a no-fly zone is unlikely in the very near future, two senior western diplomats said yesterday that Washington is considering the action in parts of Syria near the Jordanian border, a move that would require the US to bomb Damascus' air defences that lie in a densely populated part of the country.
Officially part of an annual war games exercise over the past week, Washington has moved Patriot surface-to-air missiles, war planes and more than 4,000 troops into Jordan.
Before a decision is made on any no-fly zones, Washington will likely wait and assess the impact of the new arms flow to rebels as well as the reaction by Iran and Russia.
"Having gone this far raises the odds that we'll go further," Mr Pollock said.
email@example.com with additional reporting by Reuters