WASHINGTON (AFP) – The United States is waiting to see a Russian proposal to put Syria’s chemical weapons stock under international control, but will not wait for long, top diplomat John Kerry said Tuesday.

And Defense Secretary Chuck Hagel said while everyone was hopeful the move could be “a real solution to the crisis,” he warned the threat of “credible, real” U.S. military action had to remain on the table.

Kerry, claiming U.S. ownership of the plan to rein in chemical weapons first floated Monday, said: “Yesterday, we challenged the regime to turn them over to the secure control of the international community so that they could be destroyed.”

Such a move “would be the ultimate way to degrade and deter” the arsenal held by Syrian President Bashar al-Assad, he told the House Armed Services Committee.

Russian Foreign Minister Sergei Lavrov had promised Kerry he would come up with a proposal to achieve the plan.

“We’re waiting for that proposal. But we’re not waiting for long,” Kerry said.

He vowed that President Barack Obama — who is due to address the nation later Tuesday — “will take a hard look at it, but it has to be swift. It has to be real. It has to be verifiable,” Kerry insisted.

And he warned it would be “exceedingly difficult.”

Kerry added, however, that “nothing had changed” with respect to Obama’s call for Congress to vote to approve a limited military strike on the Syrian regime, accused of using sarin gas in an attack near Damascus last month.

“We must be very clear-eyed and ensure that it is not a stalling tactic by Syria and its Russian patriots,” Hagel said of the Russian proposal.

“The threat of a U.S. military action, the credible, real threat of U.S. military action, must continue as we are talking today,” he insisted.