Russian President Vladimir Putin raised possibility that Russia could supply weapons to North Korea after the signing of a defense pact with Pyongyang, is "incredibly troubling", US State Department spokesman Matthew Miller said, Reuters reported, quoted by BTA.
Putin suggested after visiting North Korea this week that such arms deliveries to the isolated but nuclear-armed country would be a mirror response to Western arming of Ukraine.
He also warned that US ally South Korea would make a "big mistake" if it decided to supply arms to Ukraine, and that Moscow would respond to such a move in a way that would be painful for Seoul.
"It is extremely disturbing," Miller said at a briefing when asked about Putin's mention of possible arms deliveries to North Korea.
"This would, of course, destabilize the Korean Peninsula and potentially ... depending on what kind of weapons they provide, could violate UN Security Council resolutions that Russia has supported."
The treaty signed by Putin and Kim Jong-un on Wednesday obliges each side to provide immediate military assistance to the other in the event of armed aggression against one of them.
White House national security spokesman John Kirby said it was a cause for concern but not a surprise. He said that Russia's need for such foreign aid is a sign of desperation.