South Korea's military said on Friday that it suspects North Korea is preparing to send more troops to Russia to fight Ukrainian forces, even after suffering losses and seeing some of its soldiers captured.

It will mostly be missile and artillery troops who typically operate hundreds of tubed and rocket artillery systems as well as the KN-23 short-range ballistic missiles Pyongyang has already provided Moscow,

Russia signed a strategic partnership treaty with Iran on Friday that follows similar pacts with China and North Korea. All three countries are adversaries of the United States, and Russia has used its ties with them to help blunt the impact of Western sanctions and boost its war effort in Ukraine.

All North Korean recruits are taught a song that includes a verse about saving their last bullet for themselves to avoid capture, one former soldier told NBC News.