PARIS — Momentum to avoid Western missile strikes on Syria intensified Tuesday, as President Bashar Assad’s government accepted a plan to turn over its chemical weapons stockpile and France pitched a U.N. Security Council resolution to verify the disarmament.

With domestic support for a strike uncertain in the United States and little international appetite to join forces against Assad, the developments had the potential to blunt a thorny diplomatic problem and allow the Obama administration to back away from military action.

But neither effort attempts to end or even address the civil war that has left more than 100,000 dead in Syria and the main opposition bloc dismissed the chemical-weapons plan as a largely meaningless measure that would allow Assad free rein to fight on with conventional weapons.

Syria’s foreign minister said the government would accept a plan from Russia, its most powerful ally, to give up its chemical weapons in order “to thwart U.S. aggression,” offering a diplomatic option for how to respond to the Aug. 21 chemical weapons attack that the Obama administration, France and others blame on Assad.

Damascus denies its forces were behind the attack. The U.S. has said more than 1,400 Syrians died; even conservative estimates from international organizations put the toll at several hundred.

France, a permanent member of the 15-nation Security Council, will start the process at the United Nations on Tuesday under Chapter 7 of the U.N. Charter, which is militarily enforceable, Foreign Minister Laurent Fabius said at a news conference organized shortly after meeting with the French president.

President Barack Obama threw his support behind the resolution even as he pushed the idea of U.S. airstrikes against Assad’s regime if that effort fails. British Prime Minister David Cameron said his country would join France and the U.S. in putting forward the proposal.

Fabius said the French resolution would demand that Syria open its chemical weapons program to inspection, place it under international control, and ultimately dismantle it. A violation of that commitment, he said, would carry “very serious consequences.” The resolution would condemn the attack and bring those responsible to justice, he said.

Fabius expressed caution that French authorities “don’t want to fall into a trap” that could allow Assad’s regime to skirt accountability or buy time.

“We do not want this to be used as a diversion,” Fabius said. “It is by accepting these precise conditions that we will judge the credibility of the intentions expressed yesterday.”

The details and timeframe of the French proposal remained vague, but Fabius said he expected a “nearly immediate” and tangible commitment from Syria. Within two hours, he had a response from his Syrian counterpart, Walid al-Moallem.

“We agreed to the Russian initiative as it should thwart the U.S. aggression against our country,” he said.

Moallem’s comments amounted to the first formal admissions by top Syrian officials that Damascus even possesses chemical weapons. In interviews aired as recently as Monday, Assad repeatedly refused to acknowledge whether his regime did.

Russia is now working with Damascus to prepare a detailed plan of action that will be presented soon, Foreign Minister Sergey Lavrov said. Russia will then be ready to finalize the plan with U.N. Secretary-General Ban Ki-moon and the Organization for the Prohibition of Chemical Weapons.

Obama, who was scheduled to give a nationally televised address on Syria on Tuesday night, reached back into history — and the Cold War rivalry between the United States and the Soviet Union — to make his case against Syria, even as he cautiously welcomed the early developments.

“The key is, to paraphrase Ronald Reagan, that we don’t just trust, but we also verify,” Obama told CBS. “The importance is to make sure that the international community has confidence that these chemical weapons are under control, that they are not being used, that potentially they are removed from Syria and that they are destroyed.”

Obama said the idea actually had been broached in his 20-minute meeting with Russian President Vladimir Putin last week on the sidelines of an economic summit in St. Petersburg, Russia. Obama said he directed Secretary of State John Kerry to have more conversations with the Russians and “run this to ground.”