U.S.-Russia talks over eliminating Syria’s chemical weapons began here Thursday on a wary and stilted note, as Secretary of State John F. Kerry said U.S. military forces remain poised to attack Syria if a credible agreement is not rapidly reached and implemented.

Syrian President Bashar al-Assad added to the tension by saying that he is willing to place his chemical arsenal under international control — but only if the United States stops threatening military action and arming rebel forces trying to unseat him.

Assad, in an interview with a Russian television station, said he is prepared to sign the international convention banning the 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 as he headed into an initial meeting with Russian Foreign Minister Sergei Lavrov.

“The words of the Syrian regime, in our judgment, are simply not enough,” he said.

After an hour-long session to outline the logistics and agenda for the talks, both men and their deputies departed for a joint dinner, while U.S. and Russian teams of technical experts stayed behind to iron out the details. A senior State Department official said the full delegations would reconvene Friday morning.

The emergency talks are aimed at laying down a blueprint for international seizure of the weapons that the United States has said Syrian forces used to gas to death more than 1,400 people last month near Damascus. Russia, Syria’s main international backer and arms supplier, offered Monday 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 for its chemical weapons use.

The legislation, an uphill battle for Obama amid lawmakers’ skepticism, is on hold pending the outcome of what are likely to be two days of talks in Geneva. The pause button also has been hit at the United Nations, where the United States, Britain and France have 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, 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 on 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 of preferring “brute force” over democracy. Noting Obama’s reference to “American exceptionalism” 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 last month’s 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 joint 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 U.N. Secretary General Ban Ki-moon, 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 still 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.

Kerry also met Thursday with Lakhdar Brahimi, the U.N.-Arab League envoy for Syria, and spoke by telephone with the leader of the Syrian Opposition Coalition and with Gen. Salim Idriss, the rebel military commander.

The rebels have expressed dismay at Obama’s decision to call off military strikes while the diplomacy plays out. A State Department official said Kerry made clear to them that he was seeking “tangible commitments” to “a strong, credible and enforceable agreement” and “reiterated that President Obama’s threat of military action very much remains on the table.”

No Syrians were expected to attend the Geneva negotiations.

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