The U.S. is expected to announce Tuesday it is sending an additional $150 million in critically needed munitions to Ukraine, as Russia accuses Ukraine of using U.S.-provided munitions to strike inside Russia or Russian-held territory, according to two U.S. officials.

On Monday, Russia summoned the American ambassador to protest what it says was the use of U.S.-made advanced missiles in a Ukrainian attack on Crimea on Sunday that reportedly killed four people and wounded more than 150.

Crimea, which Russian seized from Ukraine in 2014 in a move that most of the world rejected as unlawful, long had been declared a fair target for Ukraine by its Western allies.

However, the Pentagon said last week that Ukraine’s military is also now allowed to use longer-range missiles provided by the U.S. to strike targets inside Russia if it is acting in self-defense. Since the outset of the war, the U.S. had maintained a policy of not allowing Ukraine to use the weapons it provided to hit targets on Russian soil for fear of further escalating the conflict.