The commander of Ukraine's land forces, one of the most senior positions in the country's military, announced on Sunday that he was tendering his resignation, citing a lethal strike on a Ukrainian military training facility.
Ukrainian President Volodymyr Zelenskiy said he had called a meeting to examine the incident.
Major General Mykhailo Drapatyi has been in charge of Ukraine's vast wartime land army since November last year.
"This is a conscious step dictated by my personal sense of responsibility for the tragedy at the 239th training ground, which resulted in the deaths of our soldiers," Drapatyi wrote on Facebook.