More reported evidence points to North Korean troops' presence in Russia's Far East region, as intelligence authorities of Seoul and Kyiv claim that North Korea is preparing to deploy soldiers to the frontline in Ukraine in what could be Pyongyang's first major intervention in an international conflict.

Ukraine's Center for Strategic Communication and Information Security on Saturday released a video via its official X account showing what it claimed were North Korean soldiers lining up and receiving uniforms and equipment in Russia's training ground in the Far East region.

CNN revealed questionnaires with sizing for uniforms and gear written in Russian and Korean languages, which North Korean recruits were asked to fill out. According to CNN, it obtained a copy of the questionnaire from Ukraine's state-run body.

This follows other footage posted to X that purportedly showed dozens of North Korean troops moving in formation while donning military equipment.

Those media revelations aligned with Seoul's confirmation Friday that at least 1,500 North Korean troops had already been shipped to Russia's Far East region.

South Korea's National Intelligence Service also noted that these soldiers were transported from Oct. 8-13 via seven Russian naval vessels and that they were issued fake identification documents to disguise them as Russian nationals from Siberian regions such as Yakutia and Buryatia.

The NIS also claimed that over 8 million units of ammunition had been shipped to Russia since August 2023 and that a high-ranking North Korean official was spotted at a missile launch near the Russia-Ukraine war frontline.

On the same day, President Yoon Suk Yeol presided over an emergency security meeting to discuss the security impact of the North Korean soldiers' dispatch to Russia, according to Yoon's office.

Alongside Seoul's confirmation, Kyiv's military intelligence chief Kyrylo Budanov believed more than 11,000 North Korean soldiers would be ready to fight Ukraine alongside Russian forces by Nov. 1.

US Secretary of Defense Lloyd Austin told reporters Saturday he could not immediately confirm the media report, but Washington would look into the case further.

"I can't confirm those reports at this point," Austin said Saturday during a news conference on the sidelines of the Group of Seven Defense Ministerial meetings in Naples, Italy.

"If that's true, it's serious, (it's) something that we'll continue to watch," he said.

Austin added that the signs also indicate Russian President Putin "is having trouble."

"We know that (Putin) continues to lose a lot of people," he said, reiterating his earlier estimate that at least 350,000 people have been killed or wounded since Russia's full-scale invasion of Ukraine in February 2022.

North Atlantic Treaty Organization Secretary General Mark Rutte said during a joint press conference with Ukrainian President Volodymyr Zelenskyy Thursday that North Korea's support in Russia with supplies of weapons and technologies among others is "highly worrying" but said NATO has "no evidence that North Korean soldiers are involved in the fight."

Zelenskyy commented that North Korea "sent tactical personnel and officers to Ukraine on (temporarily) occupied territories" and that an estimated 10,000 North Korean soldiers were "preparing on their land." Zelenskyy, however, believed Thursday that the North Korean soldiers had not yet been moved to Russia or Ukraine.

In June, North Korean leader Kim Jong-un and Putin signed a comprehensive strategic partnership treaty with provisions for military aid in the event of an armed invasion. Putin submitted a bill to ratify the treaty on Oct. 14 to Russia's lower legislative house.

In response to the move, US State Department spokesperson Matthew Miller said Wednesday that Washington "continue(s) to have great concerns about the growing security relationship between Russia and North Korea."