U.S. Secretary of State John Kerry and his Russian counterpart, Sergei Lavrov, are in Geneva for talks on disarming Syria's chemical weapons program.
But differences emerged at the outset of negotiations.
"This is not a game,"
Kerry said the option of U.S. military strikes against Syria -- in response to a suspected chemical weapons attack - remains on the table.
SOUNDBITE: U.S. SECRETARY OF STATE JOHN KERRY SAYING:
"President Obama has made clear that, should diplomacy fail, force might be necessary to deter and degrade Assad's capacity to deliver these weapons."
But Lavrov made it clear Russia wants the U.S. to set aside its military threats, if diplomatic efforts are to succeed.
SOUNDBITE: RUSSIAN FOREIGN MINISTER SERGEI LAVROV SAYING:
"We proceed from the fact that the solution of this problem will make unnecessary any strike on the Syrian Arab Republic."
That sentiment was echoed by Syrian President Bashar al-Assad.
He told Russian television he will give up his chemical arms only when Washington stops threatening military action.
SOUNDBITE: SYRIAN PRESIDENT BASHAR AL-ASSAD SAYING:
"When we see that the U.S. really wants stability in our region and will stop threatening and aiming to attack, and stops supplying weapons to terrorists, then we will consider the process can be brought to the final stage."
Washington brushed aside those remarks, and negotiations are set to continue into a second day.