Secretary of State John F. Kerry plans to discuss the plan with top Russian officials in a visit to Moscow on Thursday. As I first reported last month, the administration is proposing joining with Russia in a ramped-up bombing campaign against Jabhat al-Nusra, al-Qaeda’s Syria branch, which is also known as the Nusrah Front. What hasn’t been previously reported is that the United States is suggesting a new military command-and-control headquarters to coordinate the air campaign that would house U.S. and Russian military officers, intelligence officials and subject-matter experts.

Overall, the proposal would dramatically shift the United States’ Syria policy by directing more American military power against Jabhat al-Nusra, which unlike the Islamic State is focused on fighting the regime of Syrian President Bashar al-Assad. While this would expand the U.S. counterterrorism mission in Syria, it would also be a boon for the Assad regime, which could see the forces it is fighting dramatically weakened. The plan also represents a big change in U.S.-Russia policy. It would give Russian President Vladi­mir Putin something he has long wanted: closer military relations with the United States and a thawing of his international isolation. That’s why the Pentagon was initially opposed to the plan.

Yet for all this, it’s not at all clear that the plan will be accepted by Putin — or that Russia will fulfill its terms if he does.