Rep. Adam Schiff, a senior member of the House Intelligence Committee, analyzes Syrian President Bashar al-Assad’s offer to cede control of his chemical weapons to the international community. (The Washington Post)

A proposal for an international peace conference to end the brutal Syrian civil war could be revived if negotiations over ridding the country of chemical weapons succeed, top U.S. and Russian diplomats said Friday.

The remarks by Secretary of State John F. Kerry and Russian Foreign Minister Sergei Lavrov were the first explicit indication that the diplomacy begun this week to resolve the immediate crisis of threatened U.S. military strikes could be a gateway to a broader negotiation aimed at ending the 21 / 2-year-old conflict.

The United States and Russia had floated the idea months ago of hosting a peace conference to bring together the Syrian regime of President Bashar al-Assad and the rebels trying to unseat him. The proposal went nowhere.

Kerry began the second day of hastily arranged disarmament talks by saying that the potential for reviving the peace conference option “will obviously depend on the capacity to have success here.”

So far, there is little evidence that the U.S. and Russian negotiators are making progress.

Who has signed the Chemical Weapons Convention?

In New York, U.N. Secretary General Ban Ki-moon said Friday that the Assad regime “has committed many crimes against humanity” and that he believes U.N. investigators will issue “an overwhelming report” showing that chemical weapons were used outside Damascus last month, the Associated Press reported.

Ban made the comments shortly before the chief chemical weapons inspector, Ake Sellstrom, said the report was complete and would be delivered to Ban this weekend. Ban thought his remarks to a women’s group were not being broadcast, but they were shown on U.N. television, AP said. It will be up to Ban to decide when to release the report publicly, Sellstrom told the news agency.

In his speech to the Women’s International Forum, Ban said the Syrian civil war has created “a lost generation of children and young people” and led to “rising sectarian tensions, regional instability, the largest displacements of people in a generation, grave violations of human rights, including sexual violence,” AP reported.

“The latest fighting has also raised the specter of chemical warfare, which, if confirmed by the U.N. investigation mission, would be an atrocious violation of international law,” Ban said.

Kerry warned Thursday that U.S. military forces remain poised to attack Syria if a credible agreement to make Syria give up one of the world’s largest stores of chemical weapons is not rapidly reached and implemented.

Assad added to the tension by telling a television interviewer that he is willing to place his arsenal under international control — but only if the United States stops threatening military action and arming rebel forces.

Assad said he is prepared to sign the international convention banning chemical weapons and would adhere to its “standard procedure” of handing over stockpile data a month later.

Kerry made clear that he had a much shorter time frame in mind and that Assad was not a party to the negotiations. “There is nothing ‘standard’ about this process,” Kerry said Thursday. “The words of the Syrian regime, in our judgment, are simply not enough.”

On Friday, he and Lavrov met with the U.N.-Arab League representative for Syria, veteran diplomat Lakhdar Brahimi. They said the talks have been productive and would continue Friday and perhaps into Saturday. In addition, the two diplomats said they have agreed to meet again in about two weeks, when both diplomats will attend the U.N. General Assembly’s annual gathering in New York.

Separately, the State Department announced Friday that Kerry will travel to Jerusalem on Sunday to have an in-depth discussion with Israeli Prime Minister Benjamin Netanyahu on the final status negotiations between the Israelis and Palestinians. Kerry met with Palestinian President Mahmoud Abbas in London on Monday. A spokeswoman for Kerry said he will also talk with Netanyahu about developments in Syria.

The Kerry-Lavrov talks in Geneva are aimed at forging a blueprint for identifying and seizing chemical weapons that the United States says Assad’s government used to kill more than 1,400 people last month.

Russia, Syria’s main international backer and arms supplier, offered to negotiate the issue after President Obama sent U.S. warships to the Mediterranean and asked Congress to authorize a military strike against the Syrian government as a punishment for its alleged chemical weapons use.

The proposed legislation, an uphill battle for Obama amid lawmakers’ skepticism, is on hold pending the outcome of the talks in Geneva. The pause button has also been hit at the United Nations, where the United States, Britain and France had been readying a Security Council resolution designed to authorize the use of force if Syria does not adhere to any U.S.-Russia agreement on the weapons.

An open letter from Putin

As Kerry and Lavrov met behind closed doors Thursday, public statements flew from Moscow to Washington and back again.

Russian President Vladi­mir Putin, in an open letter to “the American people and their political leaders” published in the New York Times opinion pages, said any use of force was a violation of international law and would constitute an illegal “act of aggression.”

The United States, he said, was developing a habit of military intervention that had given the country an image “not as a model of democracy but as relying solely on brute force.” Noting Obama’s reference to America as an “exceptional” nation during a Tuesday night address to the nation on Syria, Putin wrote, “It is extremely dangerous to encourage people to see themselves as exceptional, whatever the motivation.”

“There are big countries and small countries, rich and poor, those with long democratic traditions and those still finding their way to democracy. Their policies differ, too,” he wrote.

Obama did not directly respond during brief remarks at the opening of a Cabinet meeting at the White House. He said he was “hopeful” that the Geneva talks would yield “a concrete result.”

Later, White House press secretary Jay Carney said it was “clear that President Putin has invested his credibility in transferring Assad’s chemical weapons to international control and ultimately destroying them. This is significant. Russia is Assad’s patron and protector, and the world will note whether Russia can follow through on the commitments that it’s made.

“As for the editorial,” Carney said, “you know, we’re not surprised by President Putin’s words. But the fact is that Russia offers a stark contrast that demonstrates why America is exceptional.” Putin’s government, he added, was “isolated and alone” in backing Assad’s assertions that Syrian rebels were responsible for a chemical attack.

On Capitol Hill, lawmakers were even less diplomatic. House Speaker John A. Boehner (R-Ohio) said he was “insulted” by Putin’s article.

Despite the tensions, Kerry said the United States is serious “about engaging in substantive, meaningful negotiations even as our military maintains its current posture to keep up the pressure on the Assad regime.”

He added that diplomacy cannot become a delaying tactic.

“This is not a game,” he said, as the talks began in this Swiss city, once the site of historic U.S.-Russia arms-control talks and the original international covenant banning chemical weapons as a tool of war.

Kerry and Lavrov did not take questions at their appearance before reporters. Lavrov made a point of saying that the discussions should “move this situation from this current stage of military confrontation.”

“We proceed from the fact that the solution of this problem will make unnecessary any strike on the Syrian Arab Republic,” he said through an interpreter.

Kerry responded that it was only the threat of military action that had created the diplomatic opening and that the United States will remain ready to strike.

International inspections

In a briefing for reporters traveling with Kerry, senior State Department officials said the U.S. delegation would present the Russians with information about sites where U.S. intelligence suspects Syria’s estimated 1,000 tons of chemical weapons are stored. Officials expect the Russians to provide their own assessment, presumably with information furnished by the Syrian government.

The officials, who spoke on the condition of anonymity, said they also expected to discuss security concerns regarding international arms inspectors. “We’ve suggested to the Russians they come prepared to discuss it, as well. It is certainly not a permissive environment,” one official said.

Farhan Haq, a spokesman for the U.N. secretary general, told reporters that the United Nations has received a document from the Syrian government indicating its commitment to accede to the Chemical Weapons Convention. It was not clear whether the document, which he said was written in Arabic and was being translated, included any preconditions.

“This starts the process” of becoming a member of the convention, Haq said.

Security Council members are expected to meet Monday, when Ban would brief them on the findings of a U.N. chemical weapons team that probed the Aug. 21 attack.

The inspection team was mandated only to determine whether the attack had occurred, not to affix blame. But a senior Western official at the United Nations said the inspectors collected “a wealth” of evidence that formed a circumstantial case against Assad’s forces.

In his Tuesday interview with Russia’s Rossiya 24 television, Assad said “terrorists,” the term he has long used to refer to rebel fighters, “are trying to incite a U.S. attack against Syria.” Repeating his charge that the rebels were responsible for the chemical attack, he said that “there are countries that supply chemical substances” to the Syrian opposition.

It was only Tuesday that Assad’s government acknowledged for the first time the existence of its chemical weapons stockpile. Although Assad said he had agreed to sign the arsenal over to international control, he insisted that it would happen only “when we see that the United States truly desires stability in our region and stops threatening and seeking to invade,” as well as supplying the rebels.

DeYoung reported from Washington. Will Englund in Moscow, Colum Lynch at the United Nations and Ed O’Keefe in Washington contributed to this report.