Russia's failure to strip the Syrian government of its chemical weapons stockpile contributed to the death of more than 70 Syrian civilians attacked with sarin gas, U.S. Secretary of State Rex Tillerson has alleged.

Speaking on U.S. television on Sunday evening, Tillerson said that Moscow had failed in its pledge to remove Syria's chemical weapons from the grasp of its ally, President Bashar Assad. Russian President Vladimir Putin had promised both to dispose of the weapons and monitor the regime as part of a deal made in 2013

“The failure related to the recent strike and the recent terrible chemical weapons attack, in large measure, was a failure on Russia's part to achieve its commitment to the international community,” Tillerson said on ABC's “This Week.”

“I hope that Russia is thinking carefully about its continued alliance with Bashar al-Assad, because every time one of these horrific attacks occurs, it draws Russia closer in to some level of responsibility.”

More than 70 civilians died after being hit by sarin gas in the Syrian province of Idlib on Wednesday.

The United States, Britain and the EU have blamed Syrian government forces for the assault, alleging that Assad's troops dropped the gas from planes traveling over the area.

Moscow instead says that a Syrian airstrike had hit a “terrorist warehouse” containing an arsenal of “toxic substances,” spreading gas across the local area.

The attack led U.S. President Donald Trump to launch a rocket strike against the government-held Al Sharyat air bas close to Homs in retalliation.

Tillerson, who is set to visit Moscow on Wednesday, defended the strike as “proportional,” despite claims from the Kremlin that it violated international law.

The former oil executive also stressed that the attack did not mark a dramatic change in U.S. foreign policy.

“This strike — and I think the president was very clear in his message to the American people — this strike was related solely to the most recent horrific use of chemical weapons,” Tillerson said.

Tillerson also said that the United States would not send troops in a bid to overthrow the Assad regime.

“We've seen what that looks like when you undertake a violent regime change in Libya. I would argue that the life of the Libyan people is not all that well off today. Any time you go in and have a violent change at the top, it is very difficult to create the conditions for stability longer-term,” he said.

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Russian 'Failure' Led to Syria Gas Massacre, Says Tillerson