Ukraine fired British-made Storm Shadow cruise missiles into Russia for the first time on Wednesday, targeting the Kursk region in a significant escalation of the conflict. The strikes, reportedly involving up to 12 missiles, were confirmed by Russian war correspondents and video evidence, though Ukraine’s military has not officially commented.

The missiles, with a range of over 250 km (155 miles), struck areas deep inside Russian territory, with videos showing explosions and black smoke rising. The use of Storm Shadows follows Ukraine’s deployment of U.S.-supplied ATACMS missiles a day earlier, after receiving approval from Western allies to target Russian rear bases.

Moscow condemned the attacks, labeling them a dangerous escalation. Russian authorities also warned of potential retaliation against NATO countries supporting Ukraine’s long-range missile capabilities.

The strikes come as Western countries bolster support for Ukraine ahead of a U.S. administration change. The Biden administration announced $275 million in military aid and moved to forgive $4.7 billion in Ukrainian loans. Meanwhile, the U.S. embassy in Kyiv temporarily closed on Wednesday, citing threats of significant air attacks.

The conflict, now in its 1,000th day, has intensified, with nearly 20% of Ukraine’s territory under Russian control and North Korean troops reportedly deployed to support Moscow. Both sides appear to be positioning for potential peace talks under President-elect Donald Trump, who has vowed to end the war but criticized current levels of U.S. aid to Ukraine.