U.S. Secretary of State John Kerry met Russian President Valdimir Putin in the Kremlin on Thursday to present him the new ideas. The eight-page proposal, which The Washington Post published on its website, shows the U.S. offering intelligence and targeting sharing, and even joint bombing operations. It is a pact Moscow long had wanted, but the Obama administration resisted.

The proposal would undercut months of U.S. criticism of Russia's military actions in Syria, and put the United States alongside Syrian President Bashar Assad's chief international backer, despite years of American demands for the to leave power.

Russia would get what it has wanted since intervening in Syria on Assad's behalf last September: leadership of an international anti-terrorism alliance.

Much of Washington is wary about working too closely with Russia. A dissent cable signed by 51 State Department officials last month showed a sizable part of America's diplomatic establishment believing a U.S. military response against Assad's forces was necessary.

Opposition to this latest Syria plan is shared by a significant number of officials at the State Department and the Pentagon and among U.S. intelligence agencies, according to several American officials.

Defense Secretary Ash Carter has questions about Russian activities in Syria, his spokesman, Peter Cook, said Thursday. If the Russians are prepared to do the right thing, Carter would then "be open to that conversation."

"We're not conducting or coordinating any military operations with Russia at this moment," Cook added. "And it's not clear that we'll ever reach an agreement to do so."

Earlier this week, Russia struck camps housing displaced persons and U.S.-backed Free Syrian Army fighters. A U.S. counterterrorism official said there was no presence of IS or Nusra fighters near the camps hit Tuesday. The official, who spoke on condition of anonymity because he was not authorized to publicly discuss the issue, said the camps hit had no strategic value.

The Obama administration has few alternatives to working with Russia right now.

Suggestions of U.S. force don't carry much weight, given the unfulfilled threats throughout the war. There were declarations five years ago that Assad's days were "numbered," and President Barack Obama vowed a military response if chemical weapons were used, then backed down in 2013.

The proposed U.S.-Russian "Joint Implementation Group" would be based near Amman, Jordan. At its most basic level, the former Cold War foes would share intelligence and targeting information. They "should coordinate procedures to permit integrated operations" if the U.S. and Russia decide such operations are in their interests, the leaked document said.

The proposal would address one of the most persistent problems with enforcing a cease-fire in Syria: the Nusra Front. The group is engaged in a variety of local alliances with other rebel groups the U.S. and its Arab allies want shielded by the cessation of hostilities. Nusra's fighters are often embedded with such groups on the battlefield or move between various militant formations.

For that reason, the U.S. has almost entirely avoided bombing Nusra targets in recent months. Russia hasn't hesitated. As Russia has taken out Nusra forces, the U.S. says Russia also has killed hundreds of moderate, anti-Assad fighters and civilians, undermining chances for peaceful diplomacy.

The new offer represents a new recognition by the U.S. that Nusra must be defeated to end the fighting. Its offensives southwest of Aleppo have been viewed as particularly damaging to the truce.

The document puts responsibility on Russia to get Syria's air force out of the sky, with some limited exceptions. It would subject Russian strikes against vetted Nusra targets to American approval.

Moscow's biggest responsibility would be one it has been reluctant to assume: getting Assad to start a political transition that ends his family's four-decade hold over the country. Russia supports the vague idea of "transition," but has never publicly spoken of Assad having to resign.
Reactions among U.S.-backed rebel groups in Syria were mixed.

Capt. Abdelsalam Abdurrazek, a spokesman for Nur al-Din Zenki, a CIA-screened rebel entity fighting near Aleppo, decried the U.S. for offering "to support an ally of the Syrian regime and an enemy of the Syrian people." He said his group would continue fighting alongside Nusra.

Mozahem al-Saloum of the New Syrian Army, which is fighting IS in eastern Syria, blamed Nusra for paving the way for IS, and said the U.S. plan could work if it guarantees Assad's departure. Al-Saloum, the group's spokesman, demanded "an immediate transitional period."