U.S. officials have issued repeated warnings this week about the prospect of North Korea's isolated totalitarian regime agreeing to supply Russia with ammunition and weapons for its ongoing invasion of Ukraine. But at least one of America's closest allies in Asia is just as concerned about what Kim Jong Un could get in return.

CBS News spoke Wednesday with a senior South Korean official about the Biden administration's announcement three days ago that Kim expects to meet Vladimir Putin in Russia in the coming weeks to discuss potential military cooperation.

The official said Seoul was concerned the Kim regime could be seeking nuclear-powered submarines and satellite technology from Russia, in addition to cooperation on conventional ammunition and missile technology. The official said if Russia and North Korea's bilateral ties were to extend to that level, it would highlight Kim's ability to threaten not only America's close Asian allies in South Korea and Japan, but the entire world. The New York Times first reported that North Korea was seeking nuclear submarine and satellite technology.

Remarks by Biden administration and U.S. military officials thus far have focused on what Russia stands to gain from deepening ties with Pyongyang as Moscow tries to regain momentum months into a Ukrainian counteroffensive that, while grinding on at a snail's pace, continues to make limited gains.

Both sides in the Ukraine war have faced weapons and ammunition shortages this year, and the Pentagon on Tuesday repeated its warning to North Korea "to refrain from selling ammunition and arms to Russia," which press secretary Brig. Gen. Patrick Ryder said "would unnecessarily prolong this conflict."

White House national security advisor Jake Sullivan told reporters the Kim regime would "pay a price for this in the international community" if it decided to bolster Russia's war machine, adding that it "says a lot that Russia is having to turn to a country like North Korea."

• Kim Jong Un welcomes Russia, China envoys and shows off his missiles 

Washington and its partners in Ukraine and Europe will share concern that a new pipeline of weapons to replenish Putin's stocks could enable Russia to break what has largely become a stalemate along much of the front line in Ukraine.

But in Asia, there's fear that closer ties between the Kim regime and the well-established nuclear power that is Russia could destabilize a whole other part of the globe.

Without naming Russia specifically, South Korean President Yoon Suk Yeol told fellow ASEAN bloc leaders Wednesday that any "attempt at military cooperation with North Korea that harms international peace must immediately halt."

Speaking to The Associated Press at the ASEAN summit Wednesday in Indonesia, U.S. Vice President Kamala Harris said a closer North Korea-Russia alliance would be "ill-advised."

Russia's "aggressive, unprovoked actions in Ukraine have resulted in a situation where the aura and myth of the Russian military has now been dispelled," Harris said, alluding to Moscow's failed bid to overthrow Ukraine's government and the logistical challenges its invasion has faced.

If any reciprocal deal for the provision of weapons is agreed by Kim and Putin — both of whom lead countries already straining under the weight of international sanctions — it would be in direct contravention of United Nations Security Council resolutions barring North Korea from buying or selling weapons technology. The South Korean official told CBS News that should be a concern for the entire world, not just Asia.

North Korea has carried out a series of missile tests this year, stoking tension in the region and drawing routine condemnation from the U.S. and its allies as the launches violate United Nations sanctions. The country has missiles capable of hitting targets in South Korea and Japan with nuclear warheads, and it has demonstrated an ability to reach the continental U.S. with its larger intercontinental ballistic missiles, but North Korea is not yet believed to have missiles advanced enough to deliver a nuclear warhead as far away as the U.S.

North Korea and Russia have dismissed the reports about ongoing arms negotiations and, asked on Tuesday about the claims from U.S. officials of an upcoming Kim-Putin meeting, Kremlin spokesman Dmitry Peskov said bluntly that Russia had "nothing to say on this."

Russian defense chief Sergei Shoigu said on Monday, however, that Moscow could plan joint military drills with North Korea. US officials said they're monitoring the potential for such exercises. Beijing and Moscow already conduct joint drills. It is not clear to US officials whether Beijing is on board with the potential of its client state North Korea receiving such advanced technological support from Russia.

"Why not? They are our neighbors," he said according to Russia's state-run TASS news agency.

–CBS News' Pamela Falk at the United Nations contributed to this report.

In:
• War
• Submarine
• South Korea
• Nuclear Weapons
• Ukraine
• Russia
• North Korea

Margaret Brennan

Margaret Brennan is moderator of CBS News' "Face The Nation" and CBS News' senior foreign affairs correspondent based in Washington, D.C.