The escalation of warfare in the Middle East is, if not predictable, at least hardly surprising. With it, the United States seems certain to be drawn deeper into the rebellion in Syria. President Obama should proceed cautiously yet firmly toward arming the rebels.

The stakes rose globally over the weekend with air strikes by Israel inside Syria, reportedly aimed at disrupting arms shipments to Hezbollah in Lebanon. That threatens a wider conflict that changes the calculation of whether the United States should take a more active role.

Obama has hesitated to commit U.S. arms to this conflict, and for good reason. The biggest fear is that any weapons sent to Syria could wind up in the hands of extremists and, worse, migrate to Afghanistan, where they could be used against Americans.

But the political and geographical obstacles are also significant. Russia, for reasons only it could explain, remains a devoted supporter of the murderous Assad regime. Russia’s influence doesn’t mean the United States can never act, but it certainly can influence the time and nature of any response. And the geography of Syria is far less hospitable than Libya was to action that keeps American troops from taking a direct role in the conflict.

The Israeli attack doesn’t change those factors, but its addition into the formula alters the calculation. So does the strike’s implication that Syria’s air defenses are less than advertised. The administration’s growing confidence in the reliability of the Free Syrian Army also advocates for a greater U.S. role.

Some 70,000 civilians have perished in this war and, if it is not brought to a close, it seems likely that more than that will be killed in the next two years. What is more, time clearly is running out for the Assad regime. Its survival, if not impossible, is close to it. It is a matter of when, not if.

But, to paraphrase one of Obama’s living predecessors: prudence. Americans have been at war for nearly 12 years and would surely blanch at the prospect of more Americans being killed by more roadside bombs in a new theater of war. More like Libya than Afghanistan or, worse yet, Iraq, American involvement should be limited to providing weapons and perhaps conducting air strikes that disable the Syrian military.

There is no telling how this will end. Extremists of one variety or another seem to be taking control in Egypt, and Libya remains a question mark. Syria could become a worse problem, from an international perspective, than it has been to date.

To a great extent, the outcome in Syria will be beyond our control, just as it is in Iraq and Afghanistan. What we may be able to do, by hastening the end of this civil war, is to prevent an increasingly dangerous cycle of events from engulfing and further destabilizing the entire region, and to save tens of thousands of lives.

There are no good or easy answers in this; we are left only to make the least awful choice, which is to help bring this fight to an end sooner rather than later.