GENEVA — The United States and Russia have reached an agreement that calls for Syria’s arsenal of chemical weapons to be removed or destroyed by the middle of 2014, Secretary of State John Kerry said on Saturday.

Under a “framework” agreement, international inspectors must be on the ground in Syria by November, Mr. Kerry said, speaking at a news conference with the Russian Foreign Minister, Sergey V. Lavrov.

An immediate test of the viability of the accord will come within a week when the Syrian government is to provide a “comprehensive listing” of its chemical stockpile.

“The real final responsibility here is Syrian,” a senior administration official said of the deal.

Security will be a major worry for the inspectors who are tasked with implementing the agreement; no precedent exists for inspection, removal and destruction of a large chemical weapons stockpile during a raging civil war. Mr. Lavrov said the agreement would require the cooperation of Syrian rebels and not just the government of President Bashar al-Assad. Much of the Syrian opposition is bitter about President Obama’s decision to shelve the threat of military action and to negotiate with Russia, which is a major arms supplier to the Assad government.

“This is very, very difficult, very, very difficult,” an American official said of the agreement. “But it is doable.”

At the news conference, Mr. Kerry said that “if fully implemented, this framework can provide greater protection and security to the world.”

If Mr. Assad fails to comply with the agreement, the issue will be referred to the United Nations Security Council.

Mr. Kerry said that any violations would then be taken up under Chapter 7 of the United Nations Charter, which authorizes punitive action. But Mr. Lavrov made clear that Russia, which wields a veto in the Security Council, had not withdrawn its objections to the use of force.

The joint announcement, which took place on the third day of intensive talks here, eased the United States’ confrontation with Syria.

Arms control officials on both sides worked into the night, a process that recalled the treaty negotiations during the cold war.

The issue of removing Syria’s chemical arms broke into the open on Monday when Mr. Kerry, at a news conference in London, posed the question as to whether Mr. Assad could rapidly be disarmed only to state that he did not see how it could be done.

“He could turn over every single bit of his chemical weapons to the international community in the next week. Turn it over, all of it, without delay, and allow a full and total accounting for that,” Mr. Kerry said. “But he isn’t about to do it, and it can’t be done, obviously.”

Now, however, what once seemed impossible has become the plan — one that will depend on Mr. Assad’s cooperation and that will need to be put in place in the middle of a civil war.

Mr. Kerry and Mr. Lavrov had a series of meeting on Friday, including a session that ended at midnight. On Saturday morning, the two sides reconvened with their arms-controls experts on the hotel pool deck, sitting under a white umbrella drinking coffee as they pored over the text of the agreement.

Before the news conference, Mr. Lavrov said that he had not spoken with Syrian officials while he was negotiating in Geneva. Obama administration officials say that Russia’s role was critical since it has been a major backer of the Assad government.

Titled “Framework For Elimination of Syrian Chemical Weapons,” the agreement is four pages, including its technical annexes. The agreement, which outlines procedures for “expeditious destruction of the Syrian chemical weapons program and stringent verification,” says that the United States and Russia will submit a plan in the next several days to the Organization for the Prohibition of Chemical Weapons, which oversees compliance with the chemical weapons accord.