Ukraine has used US-supplied long-range missiles for the first time, President Volodymyr Zelensky has said.
His comments follow reports that the weapons, known as ATACMS, destroyed nine helicopters at Russian bases in the country’s east.
Ukraine has not confirmed the missiles were used.
Ukraine said an air defence system and other equipment were among the targets hit in Berdyansk and Luhansk.
It added that dozens of Russian troops were killed or injured in the operation.
“They have performed very accurately. ATACMS have proven themselves,” Mr Zelensky said in an evening address posted on social media, without giving details of when or where they were used.
Russia’s military has not commented.
The Biden administration had previously refused to provide ATACMS to Ukraine but had decided “in recent weeks” to send them quietly, US media outlet reported quoting two US officials.