Ukrainian President Volodymyr Zelenskyy said that his country's army has used US-provided Army Tactical Missile Systems (ATACMS) long-range missiles for the first time in the war against Russia.
“Today I express special gratitude to the United States,” Mr Zelenskyy said in an evening video address on Tuesday.
The Ukrainian president added that the missiles “have proven themselves”.
President Joe Biden told Mr Zelenskyy in September that he would consider providing Ukraine with the missiles. Mr Zelenskyy has repeatedly pressed the US leader for the missiles to disrupt Russian airbases and networks as Kyiv mounts its counter-offensive.
“Today, special thanks to the United States. Our agreements with President Biden are being implemented,” Mr Zelenskyy said.
Earlier on Tuesday, the Ukrainian army said it had used long-range missiles to take out nine Russian helicopters at two airfields that are in Russian-held regions. The army said it also struck military equipment, an air defence system and runways. It did not comment on US media reports that ATACMS missiles were used.
The two airfields were located in the Luhansk and Berdyansk regions, behind Russia's front lines.
The ATACMS missiles that the US had delivered have a shorter range than what they are capable of out of concern to not escalate US-Russian tensions, the Associated Press reported. The version that Ukraine received has a range shorter than 300km and carries cluster munitions.
The US had previously agreed to provide Ukraine with cluster bombs, which are banned by most Nato-allied countries because they can cause civilian casualties years after a conflict ends.