Kyiv had long requested permission to use U.S. weapons to launch strikes deep into Russia before the Biden administration gave the go-ahead.

The US has been blocking Ukraine from firing long-range missiles into Russia for several months. The Pentagon introduced a review mechanism in late spring that is effectively preventing Kyiv from striking targets in Russian territory, US officials told the Wall Street Journal.

Ukraine launched a wave of drone strikes on Russia Sunday, triggering a fire at a nuclear power plant as it celebrated Ukrainian independence day against a backdrop of fading hopes