Ukraine’s President Volodymyr Zelensky said Friday that several “seriously wounded” North Korean soldiers died from their injuries after being captured by Ukrainian forces.

Russia is deploying “human waves” of North Korean soldiers, the U.S. said, and one soldier captured by Ukraine died of his injuries. Others died by suicide.

The spokesperson for the U.S. National Security Council, John Kirby, reported that soldiers from North Korea are taking their own lives, fearing for their families' fate if they surrender to Ukrainian forces.