Now that the so-called Islamic State’s caliphate in Syria is on the verge of destruction, the United States will have to make some decisions about its presence in Syria. Washington must contemplate how much military force it intends to keep in the country, but it also needs to determine what role it will play in reconstruction efforts and how deeply enmeshed it wishes to be in the messy world of internal Syrian politics.

Defining that role requires a clear understanding of American interests and a sober grasp of the realities on the ground. Interventionists both in and outside the administration argue that the United States must play a major role in containing if not rolling back Iranian influence in Syria and the region at large. This is magical thinking and is likely to draw Washington into some very poor decisions.

America can neither transform Syria nor walk away from it. Washington needs to accept the cruel reality that its role will likely be limited. Indeed, Syria is not going to emerge as a stable pro-Western polity in the orbit of or even significantly influenced by Washington. Instead, others who have the will and skill to invest there will dominate. The Trump administration would be well-advised to recognize that Syria is not (and never will be) a level playing field for the United States. Several challenging features define the operating terrain for Washington. The United States needs to acknowledge these realities for one simple reason: We will fail if we do not.

Syria is not a vital priority

There is little doubt that Syria remains a moral and humanitarian disaster and tragedy. Six years of civil war, the campaign against ISIS, and the Russian and Iranian intervention have created the largest single refugee flow since the end of World War Two, half a million dead with thousands more wounded and permanently traumatized, and reconstruction costs estimated in the hundreds of billions. But it is also a country in which this administration -- like its predecessor -- has limited interests and options, and few compelling reasons for making a major commitment.

There have been ISIS-inspired attacks and there may yet be ISIS-directed attacks against the United States as a result of events in Syria. Yet what happens there, however brutal and tragic, neither threatens the fundamental security of the homeland nor its prosperity. And despite the hemorrhaging of refugees, the rise and fall of the first proto-terror state in the modern Middle East, the continuation of a jihadist insurgency, and the expected return of foreign fighters to their countries of origin, the Syrian civil war has yet to beget the worst results predicted by interventionists. It has not destabilized Iraq, Lebanon, Jordan, and Turkey, unleashed a paroxysm of terror that has overwhelmed Europe or the United States, or led to a regional war. Some argue that the risk-averse policies of first the Obama administration and now the Trump administration have led to an abdication of America’s moral responsibility and its values. But it is important to note that the failure of the United States to rise up to stop mass killing has been the norm, not the exception, in U.S. foreign policy -- from the Nazi Holocaust to Cambodia, Rwanda, the Congo, Sudan, and Myanmar. Bosnia and Kosovo remain the sole and lonely exceptions.

The Assad regime is here to stay

However politically inconvenient and incorrect it may be to admit, it appears almost certain that the Assad regime, after being written off earlier in the civil war, has managed not just to survive but to position itself to possibly reassert control over most of the country. Bashar al-Assad’s regime controls the capital, all of the major cities, the ports and airports, and the U.N. vote. With the support of its allies, the regime has the power to survive, however ravaged the economy and damaged the military. This power may well draw others, such as the Syrian Kurds, into the regime’s orbit, since responsibility for governing areas such as Raqqa that these groups control demands resources that others are willing to provide. The international community will rightly withhold reconstruction aid or make it conditional on some kind of political transition away from Assad. But the regime will survive on the largesse of Iran and Russia, and it will strike deals with the locals.

President Donald Trump this week talked about encouraging a political transition in Syria. But this is a pipe dream, and has probably been one since the Obama administration acquiesced to the reality that from about 2015 onward, Assad wasn’t going anywhere. Together, Iran and Russia are committed to keeping an Alawite regime afloat. Nothing the boldest interventionists have proposed or will advocate in the future will fundamentally change the battlefield balance or produce a significantly different outcome.

Iranian influence can be contested (maybe) but not eliminated

It’s a bitter pill for Iran hawks to swallow, but the United States does not have the power to crush a dominant Iranian role in Syria, and Washington is unlikely to muster the will to engage the Iranians in a messy and potentially open-ended proxy war. Iran’s stake in Syria is far greater than U.S. equities in the country. Clearly Iran’s support was one of the main reasons Assad survived. This relationship is strategic in character and goes back over 40 years. Iran sought a Shia-oriented ally in a predominantly Sunni world and a window into Lebanon and the Arab-Israeli conflict. Assad looked to Iran as a source of economic and energy support and a hedge against Sunni Arabs who looked at him as an outlier.

This asymmetry means that Tehran will always be prepared to pay a higher price to defend its interests than the United States is prepared to endure to advance its priorities. Likewise, the United States cannot match the assets and allies Iran can bring to bear in Syria, and Tehran, in the face of an escalating American commitment in Syria, has escalatory options of its own in Iraq, Afghanistan, and perhaps Lebanon that could cause serious problems for the United States and its allies. The Iranian ground game would grind up U.S.-supported forces unless the United States were prepared to engage in direct combat with Iranian forces and its proxies. Congress and the American public have no appetite for another war in the Middle East. The prospects for a quick and decisive victory in such a conflict are dim, and America’s limited interests in Syria do not justify a large-scale commitment of U.S. forces or resources.

There are no grand bargains with Russia

At one time, Trump had a vision dancing in his head of a new U.S.-Russian partnership in Syria to, in his words, “knock the hell out of ISIS.” Like much of what floats around in Trump’s head, this is hallucinatory. In the first place, the United States does not need Russian cooperation to defeat ISIS. Further, Russia is in the catbird’s seat in Syria, and Moscow has no incentive to accommodate American preferences. The Assad regime is rolling up opposition forces, and the Syrian dictator, with Russia backing him to the hilt, is bent on restoring his control over the entire country.

Russia has successfully and cynically manipulated the diplomatic process and the current de-escalation zones as cover to carry out Moscow's narrow goals. These include securing and expanding bases, blocking the use of American force to remove a regime Washington doesn't like, elevating Russia's status, keeping Assad in power, and assisting Assad in regaining control of lost territory. The United States has no leverage to change the trajectory of Russian policy in Syria, and Russian President Vladimir Putin is a man who presses his advantage and never passes up an opportunity to push the United States around. Finally, Putin surely realizes that it is no longer possible to trade Russian cooperation with the United States in Syria for a lifting of sanctions related to Ukraine.

What Can America do?

U.S. risk-aversion in Syria is not without its downsides for American interests. Syria is going to remain a mess and a source of instability. The Assad regime will continue to provide a lightning rod for Sunni grievances and insurgency. Remnants of ISIS and al Qaeda will continue to operate, though constrained by continued Russian, Syrian, and American military strikes. And Iran’s rising influence will complicate Israel’s security situation, particularly if various terror groups try to operate in close proximity to the Golan Heights. But the Israelis can take care of themselves, and if they ask for American help we should and would provide it.

The administration has talked about countering Iran in the region. There has been a lot of bombastic rhetoric about how the Trump administration will roll back Iran in Syria, push to replace Assad with a better government, or challenge Russia’s primacy in the country. But administration officials have proposed no concrete actions to do this, especially in Iraq and Syria, and when this question is posed to Iran hawks it is met with silence.

There are, however, several modest and reality-based steps the United States can take. This include working with the Russians to de-conflict our respective proxies, who will continue to compete to take territory liberated from ISIS fighters; continuing drone strikes and special operations against remaining jihadists; and trying to get the Russians to limit Iranian actions that might trigger a conflict with the Israelis. We are under no illusion that Moscow will do much in regard to the latter, but Putin certainly does not want to see a major Israeli intervention in Syria that could jeopardize his gains there. Finally, we endorse wholeheartedly the suggestion of Robert Ford, America’s former ambassador to Syria, that Washington stay out of Syria and confine its engagement to helping neighboring countries deal with their refugee flows.

Almost seven years of conflict in Syria have shown that only those who are prepared to sacrifice heavily can have influence there. Even then, the country will probably seethe with discontent and violence. The United States is not willing to make the necessary sacrifices. Even if it were, there are no American solutions to what ails Syria -- and certainly none that would justify expending American lives, resources, and credibility.

