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.

In a stark warning to the West, President Putin said the attack with the intermediate-range Oreshnik missile was in retaliation for Kyiv’s use of U.S. and British longer-range missiles.

Russia President Vladimir Putin says Moscow fired a new medium-range hypersonic ballistic missile at a military facility in the south-central Ukrainian city of Dnipro, in response to what he calls Western aggression after Kyiv got the green light to fire missiles deeper into Russia.