Most critics of the White House’s proposed U.S.-Russian cooperative arrangement against terrorists in Syria, the terms of which were recently leaked, have focused on what could go wrong. Russia may simply violate the terms of any agreement reached thereby undermining the mission, embarrassing the United States, and hurting its local partners. I am far more troubled, however, by what would happen if the agreement goes as planned. A successful Joint Implementation Group (JIG) would likely weaken or eliminate a strong component of the insurgency without compensating for the lost capacity, further tilting the military balance in the regime’s favor. Unless the United States can prevent that, the JIG would make a lasting negotiated settlement in Syria more difficult than it already is, setting the stage for open-ended civil war and further radicalization.

The JIG’s terms do not overwhelmingly favor Russia, at least not on paper. They place constraints on its military action in Syria in return for intelligence sharing and possible direct operational cooperation against Jabhat al-Nusra, al-Qaeda’s Syrian affiliate. Russia would also refrain from targeting jointly designated (and presumably opposition-controlled) areas. Russia would compel the regime to ground its air force across much of Syria. Indeed, Russia might find the JIG’s terms too onerous. It can after all continue its own unrestrained war on al-Nusra and the broader insurgency alike without U.S. cooperation.

If Russia does accept the JIG proposal, it could later derail it through cheating. It could simply violate the terms, especially over target designation and rules of engagement. The document does not mention any penalties for violations, but there appear to be none. Russia may fail (or fail to try) to prevent regime aircraft from operating over “safe” areas, just as it has failed to stop the regime from violating the Cessation of Hostilities, which broke down after a few weeks. Of course, there is little goodwill between the United States and Russia over Syria anyway, meaning intelligence sharing is inherently problematic.

In theory however the JIG could unfold exactly as planned: Russia and the United States would jointly weaken al-Nusra as a serious strategic threat to the regimeRussia would limit its attacks to designated targets and areas. And regime aircraft would be grounded across much of Syria. That would save innocents from regime aerial bombardment — a worthy goal in itself. Strategically, however, the JIG should be judged by the extent that it serves key U.S. policy goals in Syria: fighting extremism and enabling a negotiated settlement to the civil war. Weakening al-Nusra will bring some temporary satisfaction, but under the current military balance it would destroy any chance of a political settlement to the civil war. It also has the potential to further radicalize Syrians fighting the regime who would be rid of al-Nusra, but then find themselves even less prepared to resist regime violence and negotiate a lasting peace.

Like any U.S. policy in Syria, the JIG can succeed only to the extent that it accounts for the main context: the civil war. Both al-Nusra and the civilian suffering that the JIG seeks to mitigate are products of this war. Since Russia intervened against the opposition in October 2015, the military balance has increasingly favored the regime, which has made and continues to make important progress against the rebels. The highly strategic province of Idlib (where al-Nusra is strongest) is the insurgency’s most critical remaining stronghold and a staging point for major operations. Here, al-Nusra fights alongside other Islamist and nationalist brigades, but it is likely the single most capable fighting force in that coalition.

The JIG would break al-Nusra as a conventional fighting force, with two important effects. First, all else being equal, without al-Nusra the opposition will lose Idlib and, with it, its position in northern Syria. The insurgency would no longer pose a strategic threat to the regime, eliminating any incentive for the latter to negotiate a meaningful political settlement with the opposition. Indeed, the regime would be well-placed to crush the remaining insurgent groups as well, including U.S.-backed fighters. A successful JIG would prevent a negotiated settlement by eliminating much of al-Nusra’s capability without replacing or compensating for the insurgency’s lost capacity. This would either prolong the war or facilitate regime progress, killing and radicalizing more Syrians.

Second, anti-regime Syrians will see the JIG as a joint U.S.-Russian war on the insurgency writ large. Unlike the Islamic State for example, al-Nusra has built considerable local Syrian acceptance, including among major insurgent groups. It is reportedly considering disassociating itself from al-Qaeda to further bind itself with other Syrian insurgent groups. It will be increasingly difficult to target al-Nusra without harming civilians and other opposition fighters. Even if the United States and Russia do so with relative success, Syrians fighting Assad know the end-results will be a weakened insurgency, an intact regime, and a legitimized Russian role in Syria. Just as predictably, this will further radicalize both insurgents and civilians in targeted areas, especially as the JIG permits regime artillery and rocket strikes on opposition territory where the United States and Russia will also be targeting.

Those wanting to fight extremists and end the Syrian war must concede that any counter-Nusra plan should not strengthen the regime, whose military confidence remains the main driver of radicalization and obstacle to a negotiated settlement. An isolated military effort against al-Nusra would greatly improve Assad’s military position. Al-Nusra should be destroyed of course, but the JIG as currently conceived would very likely sabotage broader U.S. counterterrorism and strategic interests in Syria. An anti-Nusra effort should instead be paired with direct and proxy military pressure on the regime to prevent its capitalizing on a post-Nusra opposition’s weakness. This could include increased qualitative military support to vetted insurgents and a U.S. commitment to punishing any regime targeting of civilians. There are other means, but the aim is to make the military option unpalatable to the regime. Al-Nusra should not be targeted at the price of condemning Syria to endless war and terrorism. If unaccompanied by robust U.S. measures to protect a weakening insurgency and contain an emboldened regime, the JIG will probably destroy the Syrian opposition, rule out any negotiated settlement, and replace one set of radicals with another.

Faysal Itani is a resident senior fellow with the Atlantic Council’s Rafik Hariri Center for the Middle East, where he focuses primarily on the Syrian conflict and its regional impact. Itani was born and grew up in Beirut, Lebanon. He has repeatedly briefed the United States government and its allies on the conflict in Syria and its effects on their interests.