Kyiv's forces struck an advanced Russian air-defense system in the border Kursk region, according to Ukraine's military, shortly after the U.S. green-lit attacks over the border using long-range American weapons and as North Korean soldiers are expected to join front-line clashes in the area.

Dnipro bears the brunt of Moscow's first retaliatory strike after Ukraine fires U.S.-made missiles into Russia, and Ukraine claims Moscow may have used an ICBM.

U.S. officials said the weapon fired by Moscow at the eastern Ukrainian city of Dnipro was an experimental intermediate range ballistic missile.