National Security Adviser Shin Won-sik on Wednesday lambasted North Korea as the "worst rogue group" for dispatching its troops to Russia, vowing to come up with "all possible" response measures based on South Korea's alliance with the United States.

Shin made the remark during a conference in Seoul as South Korea has confirmed some North Korean forces have arrived in western Russia, near the border with Ukraine, raising concerns they could soon join combat in the Russia-Ukraine war.

"Not only has (North Korea) provided large amounts of weapons for Russia's illegal war of aggression, it is now pushing their youth to become mercenaries for Russia," Shin said. "This is North Korea basically acknowledging itself as the worst rogue group that threatens peace beyond the Korean Peninsula and into the world."

Shin vowed to come up with "all possible" response measures based on the South Korea-US alliance and through solidarity with other like-minded countries.

Vice Defense Minister Kim Seon-ho also criticized North Korea's troop deployment to Russia at the event, calling it an attempt to elevate their ties to a "blood alliance" vis-a-vis the South Korea-US alliance.

"While closely assessing the impact the military cooperation between Russia and North Korea has on the North's strategic and tactical capabilities, we must pioneeringly strengthen the posture and capabilities of the South Korea-U.S. alliance, such as developing combined operational plans" he said.

Other participants of the conference included former commanders of the US Forces Korea, including Ret. Gen. Walter L. Sharp, Ret. Gen. Curtis Scaparrotti and Ret. Gen. Robert Abrams.

Sharp touched on the growing ties between Russia and North Korea, noting the need to prepare for a world that is heading to a "competition of great alliances."

"The alliance that is forming between North Korea and Russia -- that alliance is also in many ways with China and even with Iran, when they are trying to really look at how to destabilize the global order," he said.

"In the future, it's not about the great powers competition, it is really the competition of great alliances, and that is what we've got to be prepared to fight."