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 Russia 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.

The continued flow of U.S. munitions, which will be drawn from existing stockpiles, is intended to help Ukrainian forces repel intensified Russian attacks.

The upcoming shipment is expected to include munitions for the High Mobility Artillery Rocket Systems, or HIMARS. That system is capable of firing the longer-range missiles from the Army Tactical Missile System, or ATACMS, which Russia has said would prompt retaliation and risk escalating the conflict. One of the U.S. officials said they could not verify whether this aid package included ATACMS munitions, but said the aid did not include cluster munitions.

The officials spoke on the condition of anonymity to provide details that had not yet been made public.

The package also includes anti-armor weapons, small arms and grenades, and the highly sought after 155 mm and 105 mm artillery rounds, among other support.