The most limited U.S. option in Syria would be to carry out a set number of targeted airstrikes focused on high-value Islamic State leaders, possibly including top leader Abu Bakr al-Baghdadi. The detailed intelligence needed for such an approach would require the United States to cooperate with several regional actors. And while such strikes could degrade the Islamic State's leadership, Dempsey noted Aug. 21 that air power alone would not significantly hinder the group's capabilities. It would, however, offer a means of combating the militant group without the United States necessarily becoming entangled in the Syrian civil war, something Washington has avoided so far.
Washington could also opt for a more comprehensive approach. This could include targeting significant concentrations of Islamic State forces, their energy infrastructure or their supply depots and logistics networks across Syria and Iraq. Were the United States to pursue this course, it would need to factor in the impact of these strikes on the balance of the civil war. More directly, the U.S. Air Force would have to take into account the air power, air defenses and command and control capabilities of the al Assad regime.
In the more comprehensive scenarios, the United States would then have to choose between coordinating with the Syrian regime to determine targeting and flight parameters — preferably covertly with the help of Iraq or even Iran — or actively deterring regime interference. Both options are very risky politically. Cooperation with al Assad would open the U.S. administration to serious domestic and foreign political blowback, while the second option could derail critical nuclear negotiations with Iran, a key ally of the Syrian regime.
Ultimately, even a broader air campaign would serve only to weaken rather than cripple the Islamic State. In order to severely degrade the group's capabilities, the United States would need to get involved in the Syrian conflict in a manner similar to its involvement in Iraq. In Syria this would entail active partnership with one or more of the key belligerents in the civil war — involvement that carries its own risks.
In one version of this scenario, the United States could choose to partner with the forces fighting the al Assad regime by bolstering them with air power. Washington is already working with rebels to a large degree through a CIA program that provides arms and training. The Obama administration has also sought congressional funds to transition this into a more comprehensive U.S. Special Operations Command effort. Were the United States to partner with rebels through enhanced weapons transfers, embedded special operations forces or air power, it would upgrade the relationship significantly and risk severe blowback. The Syrian rebels are not a homogenous or unified force and their affiliations are murky and in flux. Both domestic U.S. and international critics would fault the administration for potentially directly or indirectly supporting extremist forces, especially if U.S. weapons were found in jihadists' hands. The United States would also face difficulty pushing the rebels toward fighting the Islamic State because rebel combat power is currently directed against regime forces. And any U.S. alignment with rebels would embroil it in conflict with the Syrian regime, especially while Syrian air defenses and air power are still a viable force. This, by extension, could affect nuclear talks with Iran.
Conversely, the United States could elect a gradual rapprochement with the Syrian regime in mutual support against the Islamic State. This relationship would likely have to be open; a more covert working relationship would stand in the way of comprehensive operations. The United States could do this by removing sanctions against the Syrian regime, transferring select equipment or by providing air support. This has the advantage of bolstering the U.S. position in nuclear negotiations with Iran. It would also provide a more viable means of defeating the Islamic State over the long term. This option is not viable, however, because it would necessarily involve a reversal of the current U.S. position. Abandoning rebel allies would also severely degrade U.S. alliances with Turkey, Israel and the Gulf Cooperation Council and would open the Obama administration to domestic political attacks.
Finally, there is an interim option: Washington could bolster the Kurdish People's Protection Units, known as the YPG, in a manner similar to its partnership with the Iraqi Kurdish peshmerga. One of the advantages of the People's Protection Units is that they have already proved capable in previous combat with the Islamic State. This alliance would also be of less concern to the Syrian rebels and the al Assad regime, but it would also have a smaller impact because the People's Protection Units operate only in Kurdish-populated areas. U.S. ally Turkey is also suspicious of the group because of its ties to the Kurdistan Workers' Party, or PKK, which operates inside Turkey.
The least risky scenarios the United States can pursue — limited airstrikes or alignment with the People's Defense Forces — are also the least likely to damage the Islamic State in the long run. In Iraq, the United States is pursuing cooperation through longstanding relationships with the Iraqi government and the peshmerga. The Syrian situation, however, is much more complex. In upping its chances of success, Washington also opens itself to a host of secondary risks and negative side effects. Given the administration's risk-averse nature, the United States may very well elect to pursue the independent, more limited approach in Syria. Overall, however, the fact remains that the United States has no easy options in Syria.