So many people have died in the Syrian war that the United Nations has given up counting — almost 500,000 is now the best guess. The war has also produced more than 4 million refugees, and more than 6 million people are displaced within Syria, a crisis that is straining neighboring hosts, roiling European politics, and creating the worst humanitarian crisis in the world today. ISIS meanwhile is inventing new ways to horrify the world as it seeks to govern parts of Syria and Iraq and export its terror around the world.

The Obama administration’s strategy toward Syria — prioritize the fight against ISIS over toppling Assad and partner with allies, both around the world and locally, in order to limit US involvement — has clearly fallen short. ISIS has been weakened and pushed back some in Iraq, but it is far from defeated, and Syria remains a disaster. That much is abundantly clear.

What’s not clear is what exactly the US should do instead. Republican presidential candidates have promised to destroy ISIS while somehow still keeping US involvement to a minimum, but the few plans that have been presented for how to actually do this do not adequately address the costs, risks, and limits of the strategy they’re proposing (if the plans even address those things at all).

So what are the real options for how the US could approach Syria differently? If we are considering changing course — as everyone, including myself, seems to think we should — it’s helpful to see what the actual choices are, warts and all. Without this awareness it’s easy to demand an unrealistic perfection, ignore the trade-offs inherent to all the approaches, or be blind to the costs and risks of more aggressive options.

Here, then, are five options for how the US could address the Syrian conflict. None of them are good options, but we still have to pick one, so we should try to pick the least bad one.

1) Get out and stay out: complete disengagement

The US could simply turn its back on Syria — stop launching airstrikes against ISIS, end the training program for local fighters, and give up on promoting a ceasefire and other mediation efforts. For many Americans, the Middle East is a bottomless pit that sucks in US lives and dollars, so good riddance.

But the risks would be considerable. The humanitarian horror in Syria, of course, would continue to get worse. Even more dangerous, the conflict might spread, whether through ISIS military advances, the spread of militarized and radicalized refugees, terrorist attacks (including against the US), or increased interventions by neighboring states like Saudi Arabia and Iran that turn a proxy war into a direct conflict.

2) Go all in: full-scale intervention and occupation

At the other end of the spectrum, the US and its NATO allies could intervene massively — the only sure way to crush ISIS and topple Assad. Although ISIS and Assad’s forces look big on paper, they would be no match for what the US and NATO could summon. The initial fight would be over quickly.

But what happens then? The post-2003 Iraq analogy is unfortunately apt here: The US can’t just get in and get out. Western forces would have to stay and fight the lingering ISIS, Hezbollah, and Assad loyalist forces. Washington would have to help create and install a competent transitional government — a particularly difficult task in Syria, where no one speaks for the entirety (or even most) of the moderate opposition.

Indeed, in Syria in particular — but also to some degree in Iraq — the lack of competent and moderate allies on the ground has plagued US policy, raising the question of who will take power should ISIS or other foes be defeated.

And allies would have different endgames: It’s hard to imagine the US and Europe going to war in Syria just to install a new dictatorship, but Saudi Arabia would balk at democracy in Syria, while Turkey would not want to empower Syria’s Kurds. In short, massive intervention would end one mess but create new ones.

The recent US experience in Iraq is not just an analogy, either — it’s also seen by many Americans as a cautionary tale. This means that although Americans’ support for sending ground troops into Syria has grown over the past few years, it’s unlikely that Americans would sustain the support for another massive, long-term occupation of a Middle Eastern country.

3) Get in bed with the devil: support Assad

Another alternative is to recognize how bad the potential Syrian partners are and work with the devil we know: the Assad regime.

As seasoned US diplomat Ryan Crocker contends, "As bad as he is, there is something worse." Supporters of this strategy argue that although Assad may be anti-American and a brutal dictator, at least he’s not ISIS. And since the Syrian opposition is weak, divided, and at times in bed with Jabhat al-Nusra, the al-Qaeda affiliate in Syria, it’s not like the US has good options for fighting on the ground in Syria and fostering better governance there.

To back Assad, the US could stop working with the Syrian opposition, support negotiations that accept Assad’s continued leadership, or even coordinate military operations with the regime against ISIS.

This is a miserable moral choice. Despite the US focus on ISIS, it is the Assad regime and its allies, not ISIS, that have killed the vast bulk of those who have died in Syria — perhaps seven times as many as ISIS in recent months — and created millions of refugees.

US allies Turkey and Saudi Arabia, among others, would strongly oppose this policy, either because they oppose Assad himself or because they want to sever the close ties between Damascus and Iran. The Sunni Arab world, already no big fan of the US, would loathe America even more if we were to work with Assad, as this would be seen as the US allying with the "Shia axis" (Iran, Assad, Hezbollah) against our traditional Sunni allies (basically everyone else).

4) No-fly zones, safe areas, humanitarian corridors

A commonly bruited about half-measure is to create a no-fly zone or safe area for Syrians within Syria itself: a position that has support among some Republicans and Democrats. Safe zones sound good in theory, a low-cost way to help Syrians and ease the burden on neighboring allies.

The low risk and cost of these zones may be illusory, however. The United States in essence is putting its credibility on the line, and as such would have to act if the zones are challenged. Both ISIS and Assad’s forces might see the zones as a threat, particularly if they were a base for military operations against them.

ISIS in particular might simply want to strike at anything smacking of a Western or UN presence in its theater of operations. So the zones would require a constant air presence to guard, and to prevent infiltration the United States or allies would also need troops on the ground at the zone. Assad, ISIS, or other groups might also target people as they near the zones, necessitating their expansion — and a deeper military commitment.

In addition, the zones themselves would be places of economic desperation and lost hope, while neighbors would now have a great excuse to deny Syrians fleeing the zones a sanctuary.

5) Contain the spillover

A final option is to try to "contain the spillover" — that is, to prevent the violence and chaos inside Syria from spilling over into other countries and destabilizing the rest of the region (and beyond). Or, to be more accurate, to keep it from destabilizing the region even more than it already has — remember that only a few years ago, Iraq seemed on the road to recovery — and to alleviate the problems that have already spilled over. The focus would be not just on ISIS, but also on the many other nasty actors and dangerous passions like sectarianism and apocalypticism emanating from Syria.

To do this, the US would help neighboring states such as Jordan, Lebanon, and Turkey care for the tens of thousands of Syrian refugees already in their countries as well as the thousands more who will likely continue to flow out of Syria, secure their borders with Syria, fight terrorism, and otherwise become more secure. Efforts against ISIS would continue, but the realistic goal here would be weakening ISIS to prevent it from further destabilizing the region rather than defeating it completely.

The cost of containment is low compared with most of the other options, but it’s more of a band-aid than a cure. The war in Syria would rage on, the death toll would continue to rise, and the flow of refugees would continue with no end in sight, though the risks they pose would be diminished because they are less likely to cause problems in neighboring states.

We’re stuck

If you think one of the above options is a good one, then you need to reread it. They're all bad — because they do too little to defeat ISIS and solve the horror and instability in Syria; require massive resources and time and thus are politically unrealistic; have so many risks and flaws that their worth is limited; or are morally repulsive. The lack of good allies on the ground in Syria (and, in many ways, in Iraq) is a particular limit, making it hard to consolidate any gains.

The United States should continue strikes on ISIS while it tries to promote credible local alternatives on the ground. But this effort may take years to bear fruit and may in fact never blossom, so a necessary step is to accept this reality and work to contain the spillover, to reduce the chances that the chaos and violence will engulf other allies.

Settling for "don’t let things get worse" is hardly inspiring, but the Middle East is where simple, straightforward strategies go to die. There is no perfect option — there aren't even any halfway good ones. They're all bad. But the United States needs a policy, and nobody seems to be satisfied with the current one.

Daniel Byman is a professor at Georgetown University and a senior fellow at the Center for Middle East Policy at the Brookings Institution. This article draws on his longer essay in the Washington Quarterly. Find him on Twitter @dbyman.