Back in August 2012, President Barack Obama stood behind the podium at a press conference and revealed to the world that the use of chemical weapons by Syrian government troops would change his “calculus.” His words were diplomatic, but clear: the United States would be far more aggressive in its Syria policy if Bashar al-Assad ordered the launch of chemical munitions on his own people in any way, shape, or form—and no matter how big or small. Now he has announced he will make good on that promise, and the move means the United States may be entering a new proxy war with Russia and Iran.

Suspicions that the Syrian regime had indeed deployed sarin gas in small levels against the rebels have been circulating throughout the year, with Britain, France and Israel publicly declaring that Assad had in fact crossed a line that nearly every nation regards as a crime against humanity. Months after those allegations surfaced, and months after evidence was compiled and analyzed by scientists, government investigators, and even journalists, the White House finally announced on Thursday, June 13, that President Obama’s redline had been violated.

“Following a deliberative review, our intelligence community assesses that the Assad regime has used chemical weapons, including the nerve agent sarin, on a small scale against the opposition multiple times in the last year,” the White House wrote in announcing its findings. “Our intelligence community has high confidence in that assessment given multiple, independent streams of information. The intelligence community estimates that 100 to 150 people have died from detected chemical weapons attacks in Syria to date…”

Then there was the chessboard imagery that has aided the case for war: “…The use of chemical weapons violates international norms and crosses clear red lines that have existed within the international community for decades.” Bashar al-Assad, in other words, has ignored all of the treaties and international conventions that humanity has to offer, and has now put himself in the same club as the late Iraqi dictator Saddam Hussein.

The intelligence disclosure essentially ends what had become an endless debate over Syria policy that divided the administration’s top foreign-policy officials. The question of whether it was time for Washington to intervene more forcefully, either through a no-fly zone along Syria’s borders or by sending military support to select anti-Assad rebel groups, is now answered. Doing otherwise would seriously hurt Obama’s credibility in the eyes of its allies, all of whom would then doubt whether they could take his words seriously in the future.

The questions now have shifted to execution. How many and what types of weapons does Washington feel comfortable providing? Will antitank and antiaircraft weapons be delivered to vetted rebel units—which would do heavy damage to the Syrian army’s stock of fighter jets, helicopters, and tanks? Or are small arms and ammunition the extent of the assistance? These are decisions that only Obama will be able to make, and the opposition Supreme Military Council must hope that the president will make up his mind sooner rather than later.

A report from the Wall Street Journal cites senior figures in the administration and in the Pentagon suggesting that a limited “no fighting zone” along the Syrian-Jordanian border may be established to carve out a safe area, which would provide civilians rest and the Free Syrian Army an area for unfettered training. If that option were to be seriously considered, it would represent a dramatic turnaround for a president who has tried to stay as far away from the Syrian civil war as he possibly could.

A direct U.S. military line to the Syrian rebels is designed to do one thing: stop the Assad government’s recent successes on the ground and level the playing field to a point when Bashar al-Assad will feel forced to negotiate with his opponents. Yet as noble as that plan is, this outcome presumes that the other players in the conflict—Russia, Iran, and Hezbollah—would not stand in their way.

Indeed, Washington’s quasi-intervention will not be taken lightly by the Iranians and the Russians—both of whom have demonstrated that it is in their interest to keep the current Syrian government up and running. In response to any weapons shipments from the United States, Moscow could very well decide to send an even greater amount of weaponry to the Syrian regime in order to negate any advantage the rebels would have. And it is almost inevitable that the Iranians will take the survival of Assad even more seriously in the face of U.S. and European intervention. If one thought that the thousands of Iranian military troops and advisers in Syria today was significant, United States support to the Free Syrian Army will have the undesirable effect of putting even more Iranians into the conflict.

The battle for Syria has ceased to become a civil war. It has now transformed into a regional proxy war, with Iran, Russia and Hezbollah on Assad’s side—and the United States, Europe and the Gulf on the other. And now it is a fight in which Washington is a direct investor.

Daniel R. DePetris is an independent analyst and a researcher for Wikistrat, Inc. He has been published in The National Interest, the Christian Science Monitor and the Small Wars Journal, among other outlets.

Image: Flickr/V.H. Hammer. CC BY 2.0.