It is the worst case scenario for President Obama. Syrian President Bashar al-Assad's reported use of chemical weapons in the ongoing civil war would necessitate an American intervention, despite Obama's attempts to minimize US involvement.

For a president who campaigned on extracting the United States from Iraq and Afghanistan, Syria has presented Obama with one of his greatest foreign policy challenges to date. It is a war that is unlikely to end with the overthrow of the Assad regime, a war in which the government has demonstrated a willingness to use chemical weapons against civilians and the opposition—an opposition with potential ties to terrorist organizations.

What the president decides to do will have repercussions not only in the Middle East but beyond, reaching as far away as Asia.

No appetite for war

Although President Obama acknowledged the use of chemical weapons, caution continues to dominate as questions regarding "who," "when" and "how" the weapons were used must first be answered before demanding an American response.

Still, it seems inevitable that there will be an American response of some sort, such as providing limited lethal support to vetted opposition forces or implementing a no-fly zone. While rebel forces remain competitive on the ground, Assad continues to dominate the air with planes and helicopters. Neutralizing Assad's air advantage could turn the tide of the war in the opposition's favour; however, such plans are only being considered as a last resort.

For President Obama, what is first and foremost in his mind is involving the US in another Iraq, with one thing leading to another down the slippery slope to occupation. When the Assad regime falls, would the US be willing to inherit a broken country, desperate for reconstruction, plagued with rival factions, a rising Jihadi contingent and possible sectarian violence?

A recently conducted Reuter/Ipsos poll showed support among Americans for US involvement at 10 percent, rising to 27 percent when chemical weapons are used by the Syrian government. Nevertheless, lack of support is not unexpected given a war-fatigued public; and with problems at home, Americans would rather see their leaders fix the economy rather than fight another war.

Yet, doing nothing is not in the cards. That chemical weapons have now been used has opened up a new and dangerous dimension. Fears that these weapons could find their way into the wrong hands can only be assuaged by securing the weapons with boots on the ground.

The scale of US involvement may not be anywhere near to Iraq in 2003, but Obama may now have realized that his options are severely limited. He cannot sit back and allow the Assad regime to potentially use chemical weapons again at the risk of jeopardizing America's credibility. On the other hand, Obama has little desire to fight an endless war.

American credibility at stake

Obama's response to Assad's use of chemical weapons will be closely monitored, not only by Iran and North Korea but also Israel.

For Iran and North Korea, both of whom possess nuclear aspirations in the face of international protestations, and with the North threatening doomsday on the Korean Peninsula, Syria has provided an opportunity for these countries to witness the president's resolve.

If Obama proves unable to stop a weakened Assad from utilizing chemical weapons, what reason is there to believe he can do anything against a much more stable Iran and North Korea? In the same vein, if Obama's words prove empty, what reason is there for Israel to listen to the US with respect to halting Iran's nuclear program?

Obama must respond in one fashion or another. Failure to do so would expose him, and by extension the US, as a paper tiger—all talk but no follow-through. When drawing a line in the sand, as Obama did with his "red line" warning, there must be clear consequences of crossing said line, otherwise what's the point?

The president can continue to wait for conclusive evidence on the use of chemical weapons, but it is clear that the red line has been crossed. What remains to be seen is America's response to this transgression, because there must be a response.

Implications abroad

Finding support among key players on the global stage for an international response may also be difficult to come by. Russia, given its support of the Assad regime and as a permanent member in the UN Security Council, will likely veto any US attempt to challenge Syria in the UN. This being said, the US may appeal to Russia to act, particularly given Assad's reported use of chemical weapons against not only the opposition but civilians. It should be argued to the Kremlin that these weapons, just as Washington fears, could wind their way into the wrong hands, including Chechen separatists. It is in the best interest of Russia to end this Syrian civil war as quickly as possible.

Another key player capable of affecting the outcome in the Syrian civil war is China. However, China may also be unwilling to help the US given Washington's rebalancing strategy in Asia. For China, the Syrian conflict is a necessary distraction that would draw US attention away from the Western Pacific.

Should the US find itself pulled into the Syrian conflict, the US would open up another front in another part of the world it wants nothing to do with. The result of such dilemma is that the US may be required to divert its attention, political and diplomatic if not military, again to the Middle East in order to prevent the conflict from spiraling further out of control. All of this will undoubtedly come at a consequence to American efforts in the Asia-Pacific.

The challenge for the US, then, is to manage both its objectives in curtailing further violence in the Middle East and pursuing its goals in Asia-Pacific, between removing the Assad regime from power and strengthening allegiances in the Asia-Pacific. Given that both endeavors require significant political and diplomatic attention, Washington must therefore manage its resources effectively. The Syrian conflict is not the demise of America's aspirations in Asia-Pacific, but it is most certainly a hurdle which must be dealt with immediately.

No best option

For Obama, there is no best option. Syria is a vortex that, much like Iraq, will require attention long after Assad is removed. Restoring the country's infrastructure, and ensuring that free and fair elections take place (and that terrorist-linked organizations do not seize power) will occupy any nation daring enough to take on Syria.

Although the American public has grown weary of foreign adventures, Syria simply cannot be left to its own devices, as the president is undoubtedly aware. The situation is such that politics must be removed from the equation.

Despite having run on the promise to withdraw the US from Iraq and Afghanistan, it appears fate and circumstances may force Obama to wade in. Although the degree to which the US involves itself in the country remains to be seen, what is clear is that the US will act, if only to prevent Syria's weapons stockpiles from falling into the hands of anti-American forces, and to maintain credibility abroad.

At a minimum, enforcing a no-fly zone does not appear to be outside the realm of possibility. It may be that the White House will only consider military action as a last resort; however, at this point, said time for military action appears to be fast approaching, for the chemical weapons will not remove themselves.

(Khanh Vu Duc is a part-time law professor at the University of Ottawa who researches on Vietnamese politics, international relations and international law. He is a frequent contributor to Asia Sentinel.)