Secretary of State John Kerry told Congress on Tuesday that the United States will closely monitor every step of the plan for eliminating Syria’s chemical weapons while maintaining a credible military threat against Bashar Assad’s government.

Meeting behind closed doors, Kerry briefed members of the Senate Foreign Relations Committee on the chemical weapons strategy he negotiated with Russia last week in Geneva. One of Kerry’s deputies, Wendy Sherman, spoke by telephone with House Foreign Affairs Committee members.

“He (Kerry) said that the watchwords are not ‘trust but verify,’ they are ‘verify and verify,'” Sen. Dick Durbin, D-Ill., said in summing Kerry’s message at the session. “I think it reflects the fact that we’re dealing with a war zone, civil war under way, which makes it extremely difficult and we’re dealing with questionable allies in this effort. … It is a daunting task but it will serve the world well if we can do it and make this a safer world.”

Sen. Bob Menendez of New Jersey, the committee chairman, said senators were looking for a U.N. Security Council resolution that makes the plan enforceable over the coming months.

“Each moment provides a test to see whether Assad is going to comply,” Menendez said.

The talks come amid continued diplomatic wrangling over how to collect Syria’s arsenal of chemical and biological agents to prevent any repeat of the Aug. 21 attack outside Damascus that, according to the U.S., killed more than 1,400 people, including at least 400 children.

In an interview Tuesday with the Spanish-language network Telemundo, President Barack Obama said evidence of a chemical weapons attack in Syria compiled by U.N. investigators should sway governments that were reluctant to hold the Assad regime accountable.

“What that does, I think, is change the international dynamic,” Obama said. “I think it changes international opinion on this issue. But I am also committed to saying, ‘Can we resolve this diplomatically?'”

Obama said that even if there is an agreement on chemical weapons, “we still have a destabilizing situation there and we’re going to have to take action, diplomatically, to try to resolve it. But I always preserve as commander in chief the possibility that if in fact U.S. interests are directly impacted … we may end up having to do something.”

Last week, Obama asked Senate leaders to suspend a vote on authorizing force against Syria amid deep opposition in Congress and among the American public. Kerry and his Russian counterpart, Sergey Lavrov, worked on details of a plan for Syria to turn over its weapons, and Obama and Russian President Vladimir Putin, Assad’s top international backer, are pursuing that approach through the United Nations.

“Secretary Kerry made it clear that they and the Russians are serious about Syria executing on this agreement,” Sen. Chris Murphy, D-Conn., an opponent of military action, said following the briefing. “He also made it clear that Assad, for what it’s worth, has consented to move forward with this as well.”

The early signs are promising, with U.S. and Russian officials reaching an ambitious agreement over the weekend that calls for an inventory of Syria’s chemical weapons program within a week, and its complete eradication by mid-2014. Numerous obstacles remain, however.

Moscow insisted Tuesday that any new U.N. Security Council resolution must not support the idea of the United States launching military strikes in the event diplomacy fails, challenging a persistent refrain of top American officials in recent days. And even as a U.N. report this week confirmed the use of sarin in last month’s attack, Russia blamed the rebels while the U.S. and its European and Arab allies said Assad’s forces were responsible.

In Washington, State Department spokeswoman Jen Psaki said the five permanent members of the U.N. Security Council were discussing a resolution. The U.S. and France want the enforcement mechanisms to include a military option.

“The U.S. reserves the right to take military action,” she said.

Senate Republican leader Mitch McConnell questioned whether it was possible to remove chemical weapons during a civil war.

“I’m skeptical that this is a game plan that will lead to an outcome, and it looks more like, frankly, an effort to guarantee that Assad stays in power. And as I recall, two years ago, the policy of this administration was regime change,” McConnell told reporters.

Despite toning down the rhetoric in recent days, Obama and his national security team have stressed the importance of maintaining a credible military threat. But Congress’ tepid support for any action, which is likely to grow only weaker as lawmakers focus now on the economy and averting a government shutdown, risks undermining the effort.

In the Telemundo interview, Obama called Assad a “murderous dictator” and reiterated that Assad can’t remain in power. But he said the first step to address is Syria’s chemical weapons stockpile. “We’re going to take this a step at a time,” he said.

Sen. Carl Levin, D-Mich., a leading supporter of tough action against Assad’s government, said the U.S. must show the resolve to act if either Syria or Russia backs out of the deal. “It is a continued credible threat of military force that will keep them on track to uphold the provisions of that agreement,” he said Tuesday.

Rep. Eliot Engel of New York, the top Democrat on the House Foreign Affairs Committee, spoke with the State Department’s Sherman on Tuesday and said she expressed confidence in the administration’s ability to track Assad’s chemical weapons.

No Syrian caches were hidden recently or transferred to militant groups such as Hezbollah, Engel said in a telephone interview with The Associated Press, relaying the information he received.

Democrats and Republicans are split internally over Syria. Even on Russia’s new role, lawmakers offered conflicting signs of support for Moscow’s effort.

Sen. Richard Blumenthal, D-Conn., speaking at a Senate forum, accused Russian banks of financing Assad’s government through 2½ years of civil war that has now killed more than 100,000 people and displaced millions. He said the administration should freeze Russian bank assets in the U.S. and put travel bans on employees.

“That is a pressure point that we ought to be exerting,” Blumenthal said.

Last week, he and three other senators sent a bipartisan letter to Treasury Secretary Jacob Lew demanding action against Russian financial institutions that allow Assad to “continue military purchases and pay the soldiers that sustain the war in Syria.”

(AP)