MOSCOW — The United States on Thursday offered Russia a broad new military partnership in Syria, hoping the attraction of a unified campaign against the Islamic State group and al-Qaida – and a Russian commitment to ground Syria’s bombers – could end five years of civil war. If finalized, the deal could dramatically alter America’s role in the conflict.

U.S. Secretary of State John Kerry met Russian President Vladimir 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.

“Hopefully we’ll be able to make some genuine progress that is measurable and implementable and that can make a difference in the course of events in Syria,” Kerry said.

Putin said he was looking for “tangible results.”

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 him 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.

In Washington, White House spokesman Josh Earnest said Russia had to limit its targeting to extremist groups such as the Islamic State group, also known as ISIS and ISIL, and the Nusra Front, al-Qaida’s Syrian affiliate, and not the more moderate opposition forces fighting Assad’s government.