President Vladimir Putin said Friday that Russia will continue to test and start mass-producing the hypersonic ballistic missile that it fired at Ukraine Thursday.

Tit-for-tat moves this week included the use of American-made ballistic missiles to strike inside Russia, and new nuclear threats from Moscow. Neither appear to have influenced the war on the ground.

Russia fired an intercontinental ballistic missile during an attack on the Ukrainian city of Dnipro on Thursday, Kyiv's air force said, in what would be the first use in war of a weapon designed to deliver long-distance nuclear strikes.