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.

The attack with an intermediate-range ballistic missile has spurred fears of a major escalation in the ongoing war and prompted Ukraine to request new air defenses.

Russia fired a hypersonic intermediate-range ballistic missile at the Ukrainian city of Dnipro on Thursday in response to the U.S. and UK's allowing Kyiv to strike Russian territory with advanced Western weapons,