KYIV (Kyodo) -- Around 2,000 North Korean soldiers are moving to western Russia near the Ukrainian border after completing training, a Ukrainian military source told Kyodo News on Thursday, marking the first confirmed movement of troops dispatched from Pyongyang.

On Wednesday, the U.S. government said that at least 3,000 troops from North Korea were sent to Russia earlier this month for training at military bases in the eastern part of the country.

North Korean military officers entered Russia's western Kursk region earlier this month as an advance team to prepare for the arrival of soldiers in an area where Ukraine is conducting cross-border attacks.

According to the source, the advance team is made up of about 10 officers. In Kursk, the team is believed to be securing a base to accept the North Korean troops, setting up communication networks and checking the safety of the surrounding area.

Ukrainian authorities identified the movement of North Korean soldiers through satellite data, intercepted communications and intelligence from within the Russian military.

White House national security spokesman John Kirby confirmed the troop dispatch during a press briefing on Wednesday, saying they were transported by ship between early and mid-October to eastern Russia from North Korea's Wonsan area.

The soldiers were brought in via Vladivostok in Russia's Far East, Kirby said, adding it remains unclear whether they would enter combat with the Russian military after concluding their training under way at three different sites.