The White House on Thursday warned Syria not to transfer weapons to Hezbollah, as tensions mounted following reported Israeli raids on a military research center and a weapons convoy.
"We've been very clear that Syria should not further destabilize the region by transferring, for instance, weaponry to Hezbollah," said Ben Rhodes, a deputy US national security advisor.
"We also, of course, have been very clear beyond that that we're closely monitoring Syria's chemical weapons as well," he said.
Rhodes, asked about Iranian and Syrian threats to retaliate against Israel, said that such rhetoric from Tehran showed how concerned leaders there were about the prospect of President Bashar al-Assad's regime falling.
"What we would like to see from other countries, including Russia, is an acknowledgment that Bashar al-Assad must go and that there needs to be a transition within Syria to a new government," said Rhodes.
On Wednesday, Syria accused Israel of staging an air raid on a military research center, a day after a peace envoy issued a fresh warning of the 22-month conflict spilling over into neighboring states.