Kremlin spokesman Dmitry Peskov, commenting on reports that Ukraine may use U.S.-made ATACMS missiles in Russia's Kursk region, said on Tuesday that the Russian military was monitoring the situation very closely.

President Joe Biden's administration has allowed Ukraine to use ATACMS missiles to strike deep into Russia, two U.S. officials and a source familiar with the decision said this weekend, in a significant reversal of Washington's policy in the Ukraine-Russia conflict.