These U.S. personnel are some of the first the Pentagon has acknowledged have entered Ukraine since Russia launched its large scale invasion of the country in February.

The senior defense official who spoke on background during an official Pentagon event, said, "U.S. personnel have recently resumed on-site inspections to assess weapon stocks in country whenever and wherever the security conditions allow." The official said "the return of our defense attaché and Office of Defense Cooperation personnel in country has allowed us to resume this critical function."

The U.S. Defense attaché for Ukraine is U.S. Army Brig. Gen. Garrick Harmon.

The Biden administration ordered U.S. troops out of Ukraine in February just days before Russia launched its invasion. The Associated Press reported the administration did return some troops to provide security at the U.S. Embassy in Kyiv earlier this year.