America's friends and allies in the Middle East depend on the strategic vision, clarity, and resolve of the United States to deal with the multiple crises that surround them. They feel unsure, however, about the Obama administration's policy, which from their perspective appears to be timid and unworthy of America's unique stature and responsibility.

The difficulty in finding a solution to the crisis in Syria is the fact that there are many players whose interests are incompatible with one another and there is no political solution that can mitigate these incompatibilities.

In surveying the roles of the players involved, it becomes increasingly evident that arming the rebels may well be the lesser evil to end the conflict before it spills over into neighboring countries, while Syria disintegrates to the detriment of the entire region.

To that end, the U.S. must develop a comprehensive strategy, taking into consideration what we already know about each player and their stakes in the outcome of the Syrian civil war.

First, no rebel group in Syria, regardless of ideological leanings, will accept any political solution that includes President Assad and/or his top loyalists, as well as the continuing and overwhelming Iranian presence.

They will insist on ridding the country of all the elite from the Ba'ath party, military, internal security and intelligence, who have executed his indiscriminate slaughter of innocent men, women, and children and laid much of the country to ruin.

For this reason the U.S., along with its Western allies, must supply carefully vetted rebels with the weapons (surface-to-air and surface-to-surface rockets) to neutralize Assad's air power and infantry in order to give them the upper hand.

These and other weapons should be provided immediately and in quantities that could make a decisive difference and deter Islamic radicals from pursuing their own agenda following the fall of Assad.

Second, Iran has a profound interest in keeping the Assad regime in power. For Tehran, Syria is the linchpin in its strategy to become the region's hegemon. Tehran can do so only by maintaining its overwhelming influence on the predominantly Shiite crescent extending from the Mediterranean to the Gulf.

Iran will stop short of nothing to shore up Assad's hold on power and continues to provide him with weapons, military equipment, financial help, and advisors, as well as fighters on the ground.

That said, faced with American, European, and the Sunni Arab States' resolve to turn the tide in Syria and concern about the U.S. and Israel, who might be tempted to strike its nuclear facilities at a time of heightened vulnerability, may well force Iran to retreat in order to protect its own turf at home.

To be sure, the Iranian clergy must be warned by the U.S. that Tehran's deep involvement in Syria may cost them dearly and could precipitate regime change, which is the only thing that trumps any other Iranian strategic objective.

Third, Hezb'allah, Iran's proxy, has openly declared that it will fight alongside Assad's loyalists to the bitter end. Regardless of any pretenses to the contrary, Lebanon has become mired in the Syrian civil war.

Regardless of Hezb'allah's fighting skills, the rebels outnumber Hezb'allah's fighters by multiples and can inflict an unacceptable number of casualties on its forces, provided that the rebels are given the weapons they need.

The bravado of Hassan Nasrallah, Hezb'allah's leader, will be muted once hundreds of his fighters are killed while making the organization more vulnerable to Israeli attack.

Fourth, Russia has a core strategic interest in Syria; its naval base in Tartus protects its activities in the Eastern Mediterranean, which makes Damascus central to Moscow's naval strategy and energy export.

For Russia, the warm Black Sea ports are its lifeline, making its strategic interests in Syria (as distinguished from the rest of the Middle East) of paramount importance.

Russia will not make any concession that would compromise its interests and will do whatever is within its power to support the Assad regime, including supplying the most sophisticated military hardware to prevent his fall unless it can secure its interests in post-Assad Syria.

The U.S. needs to convey to the Russians its determination to turn the tide in favor of the rebels. At the same time, the U.S. along with representatives of the rebels can assure Russia that maintaining its naval base in Syria and its activities in Eastern Mediterranean will not be challenged.

As a part of a "deal" Russia and the U.S. can agree to press the "reset button," this time in earnest, and iron out some of the broader bilateral conflicting issues including trade sanctions (still officially on the books), U.S. investigations into human right abuses in Russia, the stationing of air defense systems in Turkey, etc.

In addition, the U.S. could work out a trade-off with Russia by committing itself not to establish a no-fly-zone (which in any case would be superfluous once the rebels are provided with anti-aircraft weaponry) against the sale to Syria of the highly accurate Russian-made S300 anti-aircraft missiles.

Such air-defense systems could severely compromise Israel's air superiority and may well prompt Israel to take defensive measures to maintain its edge in the air.

Fifth, although Israel has and will continue to make every effort to stay out of the conflict in Syria, it cannot control how the crisis may evolve and what could be the ramifications on its national security.

As a result, Israel established three red lines that if crossed would prompt immediate Israeli retaliation: 1) the transfer of all types of sophisticated weapons including missiles to Hezb'allah, 2) losing control of Syria's stockpile of chemical weapons, and 3) provocation by the Syrian military or any of its agents, especially Hezb'allah.

Israel has already established its credibility in this regard by attacking several targets near Damascus along with destroying a convoy of Fateh-110 missiles being transported from Iran via Syria.

The U.S. and Israel will obviously continue to collaborate in dealing with the crisis in Syria as it evolves following the U.S. initiative, but they must also clearly signal that they will not tolerate any threat to the Jordanian Kingdom.

Sixth, for the Sunni axis that includes the Arab Gulf States (led by Saudi Arabia), Jordan, Egypt, and Turkey, Syria has become the battleground against the Shiite axis comprised of Iran, Iraq, and the Alawites in Syria and Hezb'allah in Lebanon.

The ongoing sectarian carnage in Iraq between the Sunnis and the Shiites is indicative of what might happen in Syria. If Assad were to stay in power and regain the upper hand, it would be a historic victory for Iran, further bolstering its determination to acquire nuclear weapons.

Many of the Gulf States view the crisis in Syria as an opportunity to sever the Damascus-Tehran bond, thereby changing the future geopolitical outlook of the entire region to their advantage.

Considering the aforementioned, there is no political solution that can satisfy all parties concerned; concocting a political framework that defies reality will only backfire, turning a horrific situation into a tragedy of historic proportions.

The United States must take the lead and not falter in dealing with the crisis in Syria, which many of its allies fear. The lack of decisive American action would not only compromise its influence and credibility in the region but also leave a dangerous vacuum that Russia, China and Iran will be eager to fill.

Alon Ben-Meir is a professor of international relations at the Center for Global Affairs at NYU. He teaches courses on international negotiation and Middle Eastern studies. alon@alonben-meir.com Web: www.alonben-meir.com