A U.S. service member was in the back seat of an Su-27UB fighter jet that crashed in Ukraine on Tuesday, according to a U.S. military statement.

The aircraft was taking part in Exercise Clear Sky in the Khmelnytsky region when the crash occurred. The statement from U.S. Air Forces in Europe did not specify if either the pilot or passenger survived.

"The incident is currently under investigation and do not have any other information to provide at this time," the statement said. "We will provide more information as soon as it becomes available."

Clear Sky brings together military personnel from Belgium, Denmark, Estonia, the Netherlands, Poland, Romania, Ukraine, the U.K., and the U.S., according to the command.

The exercise began Oct. 8 and is concluding this week. This is the first year the exercise has taken place, and includes U.S. aircraft F-15Cs, F-15Ds, KC-135s, MQ-9s, and a C-130J.

"This exercise aims to enhance regional capabilities to secure air sovereignty and promote peace and security through cooperation, collaboration, and interoperability with NATO partners and other allies in the region," according to the command.