To Oust Assad, Pressure Hezbollah

NEWPORT, R.I. — SYRIA has put President Obama’s enlightened realism in international affairs to its stiffest test. Direct military intervention could immerse the United States in yet another open-ended Middle East war. Doing nothing would mean failing to live up to America’s humanitarian obligations and harming America’s regional interests.

But the main impediment to a political deal remains President Bashar al-Assad’s brutal intransigence. And there is something America could do to pressure him. The most powerful inducement for Mr. Assad to reach an acceptable compromise would be a loss of support from Hezbollah, the Lebanon-based, Iranian-financed Shiite militant group. In Lebanon, popular anger over Hezbollah’s intervention in Syria is rising, and the United States must exploit this opportunity, even if it means negotiating directly with Iran to rein in its Lebanese proxy.

Hezbollah has been Mr. Assad’s ace in the hole. Without the help of its thousands of fighters, Syrian government forces couldn’t have reclaimed the strategically critical town of Qusair in early June, and would be having a harder time holding Damascus and other key areas. Hezbollah, for its part, sees Syria as a conduit for arms from its patron, Iran. Better Syria be run by an ally like Mr. Assad than by hostile Sunni rebels.

But it’s not clear that Hezbollah leaders really consider the war in Syria one of necessity. Following a July 2012 bombing that killed several senior members of Mr. Assad’s national security team, Hezbollah was likely contemplating life without Mr. Assad. Then, the group’s leader, Hassan Nasrallah, abruptly decided to double down in Syria — probably, in part, on account of loyalty to Iran.

Hezbollah is the world’s most powerful nonstate militia, but the group lacks the assets of a major state army and is acutely vulnerable to overstretching. With thousands of fighters already in Syria and the ever-present possibility of another war with Israel to worry about, it is approaching the limit of what it can do to save the Assad regime. Mr. Nasrallah’s brazen openness about Hezbollah’s support for Syrian forces seems more a nervous gambit than a reflection of resolve.

Within Lebanon, Hezbollah’s support for Mr. Assad is extremely unpopular. Pro-rebel Sunnis and pro-regime Shiites have clashed in Beirut and elsewhere, and last month Syrian rebels attacked Hezbollah on Lebanese soil for the first time. Hezbollah is loath to escalate domestically for fear of provoking the buildup of Sunni militias. Meanwhile, the Syria crisis has strained the capacity of Lebanese security forces to tamp down sectarian violence, forced the prime minister’s resignation and delayed elections, fracturing Lebanon’s fragile democracy.

Hezbollah is pragmatic and places a premium on preserving Lebanon’s stability and the political legitimacy it has built there. Given the opposition’s resilience, and Lebanon’s volatility, other Hezbollah leaders may be skeptical of Mr. Nasrallah’s decision to go all-in in Syria. Iran is supplying weapons and money. But its marked reluctance to deploy combatants and take casualties in Syria also suggests that Tehran is hedging its bets.

For Hezbollah to drop its absolute support for the Assad regime, it has to be convinced that he can’t hold on to power and that a new regime won’t completely undermine Hezbollah’s interests.

The way to Hezbollah’s heart is through Iran. The Obama administration should bite the admittedly hard bullet and start cultivating Iran as a participant in negotiations for a peace deal in Syria. Iran’s newly elected moderate president, Hassan Rowhani, wants better relations with pro-rebel Saudi Arabia. And despite Iran’s insistence that its Syria policy hasn’t changed, Mr. Rowhani is likely to be less obstructionist than his predecessors and could open up space for genuine compromise. America should also be receptive to power-sharing scenarios that preserve a role for Mr. Assad’s fellow Alawites in a new Syrian government.

Washington should also incentivize reluctant anti-Assad forces, whose disunity has lately strengthened Mr. Assad, by indicating that America is prepared to increase arms shipments to moderate rebels in Syria only if they are willing to consolidate and negotiate. Tough diplomacy along these lines could also increase the internal leverage of Iranian officials with doubts about Mr. Assad’s viability while softening Iranian hard-liners.

Some Israelis have argued that the Syrian civil war usefully bogs down both the Assad regime and Hezbollah and bleeds Iran. Though superficially appealing, this rosy view is trumped by the prospect that cross-border violence could destabilize Lebanon, Jordan and even Turkey. Such a spillover could also cause the current Iranian-Saudi proxy war over Syria to escalate into a more direct and dangerous confrontation that might ultimately discourage Iran from making the nuclear compromises that the United States so badly wants.

The most promising strategy, difficult as it may be to execute, is to cut Mr. Assad’s lifeline by co-opting Hezbollah by way of Iran.