The Obama administration's decision to ask Congress to authorize the use of force in Syria will put legislators through some contentious and uncertain votes. It leaves them facing complicated politics and ideological divides within their own parties.
Most of all, though, the votes will force U.S. lawmakers to confront a Middle Eastern crisis that has confounded the world for more than two years. They'll have to consider a series of difficult and high-stakes questions about Syria, U.S. interests abroad, the future of the Middle East, the use of force and its potential to contain violence.
What follows is a brief guide to the questions that members of Congress will consider as they decide how to vote on Obama's request. The questions are daunting and, often, the answers are far from certain. Taken together, it's positively overwhelming.
1. Why should the U.S. care about Syria?
Because a lot of people are dying there in a terrible conflict that shows no signs of abating. Syria is surrounded by U.S. allies – Israel, Jordan and Turkey – which are all effected by the war. It threatens to spread instability, sectarian conflict and political competition in a part of the world that has plenty of all three. Syria is a crucial ally for Iran, which means that the war has big implications for Iran's foreign policy and its ability to cause trouble. The war is a growing haven for Islamist extremists, including groups allied with al-Qaeda.
The question of what the United States should do about Syria, if anything, is also a proxy for larger questions about America's role in the world and its willingness to use force. It touches on the legacy of the Iraq war, but also on how the United States deals with international institutions and humanitarian crises abroad.
2. Syria is a catastrophe. What does the United States stand to gain by getting involved?
The Obama administration's primary case is that the United States has a responsibility, as a global leader, to punish Syrian President Bashar al-Assad for using chemical weapons. The world has a fragile and hard-earned norm that we don't use chemical weapons in wars, no matter how brutal. If the U.S. doesn't punish Assad then no one will, and the norm against chemical weapons will be weaker. Syria and possibly other countries could be more likely to use chemical weapons in the future. Preventing that from happening would be good for the United States because we don't want to live in a world where people use chemical weapons and because we want to continue to be perceived as a global leader.
The administration also argues that the United States needs to protect its "credibility." Obama had earlier called chemical weapons a "red line" and if he doesn't respond to that line being crossed then, some worry, foreign leaders might take U.S. threats less seriously in the future. The administration also says that the United States has immediate national security interests in mitigating Syria's war, which threatens to spread into neighboring countries, although the strikes would be less about containing the war and more about deterring the use of chemical weapons.
3. What does the United States have to lose by launching strikes?
It's possible that strikes won't actually deter Assad from using chemical weapons and could even make him more likely to use them if he panics and fears he might lose otherwise. Strikes could also inflame anti-Americanism in Syria or the region more generally, leading more people to rally behind Assad. It also could kill innocent civilians – cruise missiles do miss sometimes.
The biggest concern, though, is that the United States could get sucked into a war it's worked hard, rightly or wrongly, to avoid. Mission creep happened after the U.S. invaded Iraq and Afghanistan; it also happened in Libya in 2011, when a "no-fly zone" grew into an all-out intervention against Moammar Gaddafi. The danger that limited strikes will become something more open-ended is real.
4. What if Syria or its allies strike back?
The Syrian military does not have much capability to strike back. More to the point, it's not as interested. The last thing that Assad wants is to escalate against the largest military on the planet.
While it's possible that he or an ally could launch a symbolic retaliation, Assad's interests are best served by taking his lumps and moving on.
5. Should we try to do something bigger that might end the war?
That's what some lawmakers, particularly Sens. John McCain and Lindsey Graham, have been advocating. They say the United States should take stronger military action in support of the rebels to topple Assad outright. They argue that the war is only going to drag on and get worse if we don't, and they're probably right.
The problem is that the war sprawls across many front lines and across sectarian divides. Analysts disagree about what it would take to fully defeat Assad's forces, but at the very least it would require heavy support to rebel groups, which are disorganized and often tied to anti-American extremists.
The more difficult question is what happens after we defeat Assad. One lesson that the United States learned in Iraq is that it's really hard to stop people from killing each other if they're committed to doing so and they have guns. Tamping down the sectarian violence required a massive commitment of ground troops over several costly years and even then it's not clear that it really worked.
6. Who is better for the United States, Assad or the rebels?
Neither is very good for American interests. Assad, in addition to being an oppressive dictator at home, is an anti-American leader who supports Iran and the Lebanese militant group Hezbollah. But he has at least been stable, rational and predictable. He causes trouble for the United States and its allies, but he's smart enough to stop short of anything crazy.
There's a growing fear that the rebels could be worse. Some groups say they want democracy but some openly espouse allegiance to al-Qaeda, and are already imposing a severe form of ultra-conservative Islamist rule. It's not clear who would come out on top, but political vacuums tend to empower extremists
The United States already saw this movie in Afghanistan; after an amalgam of rebel groups forced out the Soviet-backed puppet government, infighting among them led to civil war and ultimately Taliban rule. Perversely, the best way to keep this from happening in Syria is for the Assad government to retain at least some power.
7. How would strikes affect U.S. relations with the Arab world?
It sure wouldn't help. Although some Arab governments support strikes, quietly and not-so-quietly, actual Arab people tend to be deeply uncomfortable with the idea of Western military intervention in their region.
The first Gulf War, in which a U.S.-led force expelled Iraqi troops from Kuwait in 1990 and 1991, inspired pro-Saddam Hussein protests across much of the Arab world, even though Saddam himself was not particularly beloved. And the scars of the U.S.-led 2003 invasion of Iraq are far from healed. U.S. strikes on another Arab country, even if meant to ameliorate the war, are not going to help America's already-troubled image in the region.
8. How would strikes affect U.S. relations with Russia and Iran?
If you support confrontational approaches to Russia and Iran, Syria's two main allies, then strikes on Syria probably make some sense to you. Weakening Assad would weaken them as well and could, to Iran, send a message that we're willing to use force to deter weapons of mass destruction.
If you support engagement with Moscow and the effort to find a peace deal with Tehran, then strikes are going to set those missions back, particularly the latter. New Iranian President Hassan Rouhani has sent repeated messages that he wants to work toward peace with the United States. Striking Syria would put Iran in more of a defensive crouch; it could also make it tougher for Rouhani to bring more hard-line Iranians on board for peace talks.
9. Some people say a political solution would be better. Shouldn't we try that?
That's actually been the Obama administration's policy all along: to encourage Assad and the rebels to negotiate a peace deal. It would avoid the chaos of a political vacuum and could be the best way to end sectarian fighting. But it also hasn't gone anywhere in two years of fighting, first because the Assad government didn't want to negotiate and now also because the rebels are so fractured that there's no one for him to negotiate with.
A political solution would also leave some part of the Assad government in power, which is distasteful for obvious reasons. Some analysts argue that strikes could help force the Assad government to negotiate a peace deal. The model here is the 1995 Dayton Accords, when NATO-led bombings in Bosnia helped force the government to enter peace talks.
10. What happens if we do nothing?
The likely outcomes to inaction don't look so different from the likely outcomes to limited strikes. After two-plus years of deeply entrenched civil war, not to mention active meddling from regional powers like Iran and Saudi Arabia, Syria is being shaped by forces far more powerful than a few American cruise missiles. The fighting has taken on a self-perpetuating velocity that would be extremely difficult to stop.
The biggest risks of inaction for the United States are that the taboo against using chemical weapons would become a bit weaker, especially within Syria, and that the United States would be perceived as further losing some international primacy. After the U.S.'s setbacks in Egypt and its tension with Saudi Arabia over the region's future, the United States would see its influence in the region take another hit.
The biggest upside of inaction for the U.S. would be to avoid getting sucked into a terrible conflict with no obvious solution or end in sight.
11. Would voting down the president's request hurt U.S. foreign policy?
That depends on who you talk to; analysts tend to make this argument when they think Congress is about to block the president from doing something they see as worthwhile in foreign policy. In 2010, when it looked like the senate would refuse to ratify a nuclear arms reduction treaty that Obama had negotiated with Russia, a number of left-leaning analysts said that this would hurt U.S. credibility abroad by hobbling the president's ability to deliver on promises he makes to foreign leaders. And plenty of right-leaning analysts warned the same thing when George W. Bush's foreign policy was challenged by a democratic Congress after 2006.
The truth is probably that the U.S. political process is not well-understood in foreign capitals, just as Washington can often misread how Moscow or Beijing or Tehran make decisions. The United States, like any other country, is judged more on action than on rhetoric.