A Ukrainian Su-27 fighter jet lands during the Clear Sky 2018 multinational military drills at Starokostiantyniv Air Base in Khmelnytskyi Region, Ukraine October 12, 2018. A Ukrainian Air Force pilot was also killed during what the Ukrainian Defense Ministry called "a training and combat flight".
"We understand there was an American in the backseat of the aircraft", the statement said, adding that the Air Force is investigating the incident. Both the US and Ukrainian governments are investigating what caused Wednesday's crash.
The training flight was part of Clear Sky 2018, the largest aviation exercise staged in Ukraine since the former Soviet-bloc country gained independence in the early 1990s.
We will continue to update this story as more information becomes available.
The pilots were taking part in a "training and combat flight" as part of multinational military exercises with the United States and seven other North Atlantic Treaty Organisation countries.
Military prosecutors in Ukraine's Central region have launched an inquiry.
Later, U.S. Air Forces in Europe (USAFE)has confirmedthat a U.S. service member was involved in the incident, but has no made an official announcement as to their status.
"This is a sad day for the United States and Ukraine", said Maj.
The training exercise included USA aircraft from the California Air National Guard, including F-15C Eagles and a C-130J Super Hercules, in addition to an F-15D from the 48th Fighter Wing, KC-135s from the Illinois Air National Guard and the 100th Air Refueling Wing. "Aircraft from California units will include F-15C Eagles and a C-130J Super Hercules", said the Air Force.