Tillerson says to press Russia on Syrian chemical weapons

US Secretary of State Rex Tillerson will press Russia on its failure to prevent Syria's use of chemical weapons in meetings this week in Moscow, he said in interviews aired Sunday.

Tillerson stopped short of accusing the Russians of complicity in a suspected sarin nerve gas attack April 4 that killed at least 87 civilians in Syria's southern Idlib province.

"I don't draw conclusions of complicity at all, but clearly they've been incompetent and perhaps they've just simply been out-maneuvered by the Syrians," Tillerson said in an interview with ABC's This Week program.

Tillerson meets with Russian Foreign Minister Sergei Lavrov on Tuesday, just days after the United States fired cruise missiles at a Syrian air base in retaliation for the chemical attack.

It was the first time the United States has intervened directly in the Syrian civil war against the Russian-backed regime of President Bashar al-Assad.

Moscow has sought to deflect blame from its long-time ally al-Assad over the incident and says Syrian jets struck a rebel arms depot where "toxic substances" were being put inside bombs.

"Part of the discussions when I visit Moscow next week is to call upon Foreign Minister Lavrov and the Russian government to fulfill the obligation it made to the international community when it agreed to be the guarantor of the elimination of the chemical weapons and why Russia has not been able to achieve that is unclear to me."

If Syria carries out more chemical attacks, he said, "that is going to be clearly very damaging to US-Russian relations.

"I do not believe that the Russians want to have worsening relationships with the US, but it's going to take a lot of discussion and a lot of dialogue to better understand what is the relationship that Russia wishes to have with the US."

At the same time, Tillerson and other top US officials made clear that the US objective was limited to deterring further chemical attacks, and not the start of a campaign to oust Assad.

"We're asking and calling on Bashar al-Assad to cease the use of these weapons. Other than that, there is no change to our military posture," he said.

"I'm hopeful that we can have constructive talks with the Russian government, with Foreign Minister Lavrov and have Russia be supportive of a process that will lead to a stable Syria."