The U.S. military also believes it is overstretched, and with the risks of significant cuts and even “sequestration” on the horizon, it will not be eager for a costly, troop-intensive mission that has little support at home and no clear end date. The new Defense Strategic Guidance puts it bluntly: “U.S. forces will no longer be sized to conduct large-scale, prolonged stability operations.”

The idea of allies taking over in lieu of U.S. leadership is similarly implausible. European capabilities for such missions have been steadily deteriorating for some time as the Continent’s economic crisis has lingered on. Even if willing, NATO seems unlikely to have the capacity to shoulder the burden, given its capability shortfalls and least-common-denominator approach to action. Robert Gates’s stinging remarks in his last policy speech as secretary of defense laid the blame on lack of will and lack of resources, resulting in European defense budgets “chronically starved for adequate funding for a long time.”

Turkey is the country likely to do the most. It has large numbers of competent forces, its economy is robust and its citizens care about the fate of Syria. Most important, Turkey fears massive refugee flows, the spread of secessionist sentiment to its own Kurdish population, terrorist activity and other evils that could emanate from a chaotic Syria. A Turkish role should be encouraged, while remembering that Turkey is not an impartial power and it will favor Syrian groups that may be anti-American, or at least not eager to embrace Washington.

The United States will also push democracy—but here Syrians likely will take a different course than Washington wants. The big issue is whether the civic structure will be liberal, guaranteeing individual and minority rights, or majoritarian, reflecting only the interests of the Sunni Arab community. Religious minorities—particularly the Alawites but also Christians, Druze and others who enjoyed some favor during the Assad years—likely will lose their special privileges and may also suffer open discrimination or even persecution. Elections can make the problems worse. Groups may rally against one another, make chauvinistic electoral promises and sow fear within their own communities. Warlords will attempt to control and manipulate the process, with power coming out of the barrel of guns. If the new government is Islamist in orientation, the discrimination may be even more intense. While Islamists in Egypt so far have shown respect for minority rights, in Syria there likely will be more pressure to discriminate because minority communities will be painted as sympathizers of the old regime. Assad’s regime has stoked sectarian tension, and those to whom evil is done often do evil in return.

While opposition forces are indeed vocal in requests for lethal aid to break the regime’s back, it is not at all clear to what degree U.S. assistance will be solicited to fashion a post-Assad state. Lack of government legitimacy is one of the main problems facing a new Syrian nation. A conspicuous foreign presence propping up a new government, possibly at the perceived expense of certain minorities, may further undermine legitimacy.

These considerations suggest that any state-building effort should be approached with restraint, but a limited U.S. role may actually encourage neighbors to meddle. Proxy battles between regional actors such as Saudi Arabia and Iran may confound efforts to stabilize Syria without a strong intervening presence. An absent America plays into a broader narrative of a weak and faltering superpower, strength sapped by foreign battlefields in Afghanistan and Iraq. Conversely, an expansive U.S. role may likewise provoke external interference, particularly from Iran and foreign jihadists.

HOW THE United States supports regime change—and whether it should support Assad’s fall at all—should depend in part on U.S. plans for the aftermath. The long-term political objective should be a stable and democratic (or at least representative) government that both Syrians and their neighbors can live with. Helping neighbors manage refugees, police their borders, go after terrorist groups and solve other problems should be central considerations in any U.S. strategy for Syria.

Effective planning for the day after Assad’s fall, despite all the uncertainties and contingencies, is essential now. Planning involves more, however, than small cells in large bureaucracies such as the Pentagon or State Department. It involves a comprehensive effort across agencies that includes the highest decision makers. The big decisions, and the big fights, must be done in advance.

Getting significant resources for such a mission is unlikely given current fiscal constraints and the political environment. To invoke the admonition attributed to Winston Churchill, “Gentlemen, we have run out of money. Now we have to think.” Recognizing limitations up front allows for strategic and prioritized use of finite resources. Too often the United States has failed to fully grasp this imperative. It has underestimated the challenge, overestimated its own capabilities, and overpromised in extending political pledges and impassioned, intermittent pleas for intervention. All this can result in overextension. Or the United States could find itself in a middle ground on resources and commitment, with its exposure maximized and its ability to achieve its objectives limited. This would be the worst of both worlds. Instead, the best the United States is likely to manage will be a limited engagement with modest aims and a modest commitment of resources, working with the larger international community. It is better to go small and achieve less than to launch large, ambitious projects that are ultimately unsustainable.

But this does not suggest an entirely hands-off approach. Inaction has its own costs. One emerges in the battle for public opinion as Arab publics look for evidence that the United States is credible in its claims to promote democracy and human rights. Criticism already has been levied over NATO and U.S. willingness to engage in Libya, ostensibly to prevent mass atrocities, but not in Syria, where atrocities already committed long since overtook the mere threats that were present in Libya. Standing by as chaos enveloped Syria would further diminish opinion of the United States. Providing some help lends Washington greater legitimacy (and access) to weigh in on issues that it cares about, such as securing Syria’s chemical weapons and reducing Iran’s influence in a post-Assad Syria. With people on the ground, the United States also gains an intelligence advantage and is less likely to be blindsided should things go awry.

The United States also has interests in Syria that go beyond what most Syrians care about. The threat of Syria’s chemical arsenal falling into terrorist hands, for example, is a greater concern for Syria’s neighbors and the West than for Syrians, who understandably would put more focus on immediate issues of security and economic rebuilding. Washington also will be concerned about the security of Israel, which most Syrians see as an enemy. The United States should prepare for the possibility that a post-Assad crisis involving the compromise of chemical-weapons arsenals could trigger an intervention.

Any effort would require both soldiers and civilians—though preferably as few soldiers on the ground as possible. Given U.S. weaknesses on the civilian side, reaching out to the international community is essential, though it too is weak on this score. Moreover, an American-led stabilizing force would probably not be welcome in Syria, and there would be little support for a sustained presence among the American people. The United States should consider being part of a multinational body and playing a supporting role to demonstrate it is contributing to Syria’s security. Recognizing U.S. intent in pursuing a limited course of action now would help focus attention on unity of effort with partners who will augment and/or lead external state-building efforts.

But what should these people do? A multinational body of uniformed and civilian personnel could help reconstitute Syrian uniformed forces, lend expertise in setting up impartial and functional political institutions, and help restore basic services. Washington should also work with any new Syrian government to fight terrorists. Here Yemen is a model, with the United States providing a broad range of assistance and conducting unilateral actions with the fig leaf of a government claiming them as its own. Perhaps most important, the United States can help set conditions for economic recovery: rolling back sanctions, helping to repair banking infrastructure, encouraging foreign investment, and coordinating assistance from Syria’s neighbors and other parties to ensure that aid is used efficiently.

The United States also could coordinate efforts of U.S. allies. Each will come to Syria with its own interests, and a modest U.S. role means the United States cannot impose its agenda. Washington can, however, try to prevent inevitable differences from getting out of hand and push for a sensible division of labor.

Among U.S. allies, Turkey is best positioned to intervene rapidly. The so-called golden hour after Assad falls will be critical, and Turkey already will be present. Also, Turkish forces are prepared to operate in an integrated way with civilians and NATO partners, as they have done in leading two provincial reconstruction teams in Afghanistan. Gaining a NATO mandate and UN support for Turkish activities would embolden Ankara and give its moves more legitimacy. Turkey, of course, will pursue its own interests in Syria, but for the most part these coincide with America’s: Ankara wants a stable and secure Syria that has a legitimate government. The moderate Islamist regime in Turkey is likely to continue supporting moderate Islamists in Syria, but the weakness of pro-American secular forces makes this the best outcome Washington could reasonably expect.