MOSCOW (AP) — U.S.-Russia ties nosedived on Thursday after Russian leader Vladimir Putin shot back at President Joe Biden's description of him as a killer.

The back and forth underscored Biden's desire to distance himself from former President Donald Trump's perceived softness on Putin despite actions his administration took against Russia. Although Biden agreed to extend a major arms control deal with Russia, he has been notably cool toward Moscow and highly critical of many of its activities.

In taking a tough stance on Russia, Biden has said the days of the U.S. "rolling over" to Putin are...