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.

Russia launched a major invasion of Ukraine in February 2022. The recent deployment of North Korean troops to Russia is a sign of the growing alliance between the two pariah states.