Speculation over U.S. military intervention is on the rise again after the White House acknowledged on June 13 that chemical weapons had been used by the Syrian regime multiple times against the Syrian opposition last year. The acknowledgment, combined with an ambiguous pledge to increase assistance to the main armed wing of the Syrian opposition, nudges a reluctant United States toward another Middle Eastern imbroglio. But the chemical weapons narrative is not akin to the weapons of mass destruction choreography that led the United States into Iraq. On the contrary, the United States continues to be driven by hard constraints in managing its involvement in Syria.

The acknowledgement by the U.S. administration was inevitable. The United Kingdom and France had already initiated campaigns to publicize the use of the chemical weapons in Syria, urging the United States to at least acknowledge the reality. The United States, particularly after U.S. President Barack Obama broadly defined chemical weapons use as a "red line," took its time to respond, saying it would have its own intelligence agencies provide an assessment before it made a judgment on the matter. Even when that judgment was made June 13, it contained distinct caveats.

The White House statement, which came from a relatively low-ranking official, asserted outright that a red line had been crossed, changing the president’s calculus on increasing support for the rebels. The official said the president had authorized the increase of non-lethal aid and left open the question of what additional assistance would be provided to the rebels. The statement also made clear that any decision on additional aid would be coordinated with partners and allies — a diplomatic process that can conveniently be dragged out. It added that any action taken would be consistent with U.S. national interests and objectives — that the United States, in other words, is not about to be pushed into a policy it's not prepared to pursue.

The next few months will certainly test U.S. resolve to maintain this policy of restraint. After regaining control of the strategic Qusayr region — critical to holding the Homs crossroads — the Syrian regime, backed by Hezbollah and Iraqi Shiite fighters, is now concentrating its efforts on regaining control of the northern countryside on the main approach to Aleppo, a bastion of rebel support. The regime's push to Aleppo is in some ways reminiscent of the push to Benghazi by loyalists of Libyan leader Moammar Gadhafi. London and Washington characterized that push as an impending humanitarian crisis that required pre-emptive action. Certain members of the U.S. Congress who are advocating for the United States to create a no-fly zone in northern Syria over Aleppo will certainly point out the similarities.

But the road to Aleppo is treacherous. Much of the territory along the route is rebel-controlled and every mile pushed north requires fuel and ammunition. The rebels, meanwhile, have used improvised explosive devices and ambushes to great effect. The regime needed several weeks to re-establish control in Qusayr — even with the help of Hezbollah — and it is located within the regime's core sphere of influence. Fighting north through several villages and into Aleppo is a far more challenging task. Even if the loyalists are successful, they will likely incur large losses in equipment and personnel. Most of all, this military campaign will take time. Supply lines will need to be kept open and secure for loyalist forces to forge forward. Firepower will be diverted away from critical areas in the loyalist core, such as Homs and Damascus, which are still under threat from rebels. The regime, in other words, could overextend itself.

The United States will continue watching the battle closely, but not with an eye toward throwing itself into the fray. This is not just a battle among Syrians. This is a battle between Saudi Arabia and Iran, Iran and the United States, Turkey and Iran and Russia and the United States, with each player pursuing very different interests. Saudi Arabia and Iran are locked in a centuries-old rematch, where fighters today are drawing their motivation from seventh century battles. Turkey is looking for a regional opportunity to showcase itself as a model and leader for the Islamic world, but is confounded by its own ideals and domestic distractions. Russia is looking for another noisy Middle Eastern maelstrom to bog the United States down while it purses its own interests — with little U.S. interference — in the Russian near abroad.

The United States' strategic interest is to avoid becoming drawn further into another age-old sectarian vendetta that saps the United States' ability to maintain its balance in the world. Iran can exude confidence from the latest loyalist successes in Syria, but this is not a conflict that is going to end any time soon, and so will require ever-greater sacrifices from Syria’s allies to prevent the Alawites from losing ground to a Sunni majority. From the U.S. point of view, that is not such a bad thing. But responding to political challenges to do more requires great cunning and restraint. For now, that pressure is being managed through an adroitly worded press release and perhaps a slow trickle of weapons to a select group of rebels. This paradigm could always shift, but this is where we are for now.