A U.S. pilot was among two crew who died when a Ukrainian Su-27 air force fighter crashed during a training flight on Tuesday, the U.S. military said.
"We have seen reports claiming a U.S. casualty and can confirm a U.S. service member was involved in this incident," it said in a statement, adding that the circumstances of the crash were under investigation.
The two pilots, the other of whom was Ukrainian, were the only people on board.
The Ukrainian general staff earlier said the pilot and co-pilot died, without giving their nationalities.
The crash took place during Clear Sky 2018, multinational air drills involving military personnel from eight foreign countries also including Britain, the Netherlands, Poland and Estonia that started last week.