Republican Sen. John McCain on Tuesday warned against any attempt to reboot U.S.-Russia relations under Donald Trump’s presidency.

“With the U.S. presidential transition underway, Vladimir Putin has said in recent days that he wants to improve relations with the United States. We should place as much faith in such statements as any other made by a former KGB agent who has plunged his country into tyranny, murdered his political opponents, invaded his neighbors, threatened America’s allies, and attempted to undermine America’s elections,” the Arizona senator said in a statement.

Russia on Tuesday launched a major military offensive in Syria where Putin is backing Syrian President Bashar Assad.

Throughout the campaign, Trump spoke highly of Russian President Vladimir Putin and said he would improve relations between the two countries. Putin and Trump spoke after his victory last week.

“The Obama Administration’s last attempt at resetting relations with Russia culminated in Putin’s invasion of Ukraine and military intervention in the Middle East,” McCain said. “At the very least, the price of another ‘reset’ would be complicity in Putin and Assad’s butchery of the Syrian people.”