Ukraine has transferred two captured North Korean soldiers to South Korea, Ukrainian President Volodymyr Zelenskyy said, prompting Seoul to express regret that the move had been disclosed publicly despite an agreement to keep it private.

Announcing the transfer in an address to the United Nations General Assembly on Wednesday, Zelenskyy said the two men had recently been sent to South Korea after being captured while fighting for Russia in the war against Ukraine.

“These guys are not easy to capture alive. One of them, when he realized he was going to be taken prisoner, tried to kill himself. And he was shocked that fate did not let him die,” Zelenskyy said in his speech.