North Korea's military has come under the spotlight after the United States joined South Korea and Ukraine this week to accuse Pyongyang of dispatching thousands of troops to Russia, potentially to ready them for combat in the Ukraine war.

The move gives Kim Jong-un, the leader of North Korea, leverage to ask President Vladimir V. Putin of Russia for a lot in return.

U.S. National Security Adviser Jake Sullivan and his counterparts from Japan and South Korea on Friday issued a joint statement voicing "grave concern" over North Korea's move sending soldiers to Russia.