Not long ago, President Bashar Assad of Syria seemed a remote and embattled figure, with the United States threatening airstrikes and other Arab leaders denouncing him for having used chemical weapons against his own people.

Yet in recent days, he appears, paradoxically, to have turned the crisis to his advantage, making clear to a global television audience that he aims to use President Obama's own "red line" against him.

In exchange for relinquishing his chemical arsenal, Assad said Thursday, he will require that the United States stop arming the Syrian opposition — a demand that might seem wishful from the leader of an embattled country where civil war has left 100,000 dead, 2 million living as refugees and large swaths of territory beyond his control.

Assad outlined his demands, telling a Russian TV interviewer that the arms-control proposal floated by his patron in Moscow would not be finalized until "we see the United States really wants stability in our region and stops threatening, striving to attack and also ceases arms deliveries to terrorists."

Secretary of State John Kerry delivered a blunt response to Assad's comments, saying the standard procedures for identifying and securing the weapons were too slow in Syria's case. "There is nothing standard about this process," Kerry said. "The words of the Syrian regime, in our judgment, are simply not enough."

Assad hinted in his interview that the Russian proposal — which requires Syria to sign the Chemical Weapons Convention — could become a lever for endless negotiations and delays, much as Saddam Hussein delayed arms control inspectors during the 1990s. The state-owned Syrian newspaper Al-Watan put it bluntly in a headline on Thursday: "Moscow and Damascus pull the rug out from under the feet of Obama."

Assad's comments were the latest chapter in a rhetorical offensive by the Syrian president and his surrogates, who seem to feel that global perceptions of the Syrian opposition — with its strong component of Islamic radicalism — have shifted in their direction.