South Korea says it 'will not stand idly by' if North Korea receives Russian help on nuclear weapons

North Korean leader Kim Jong Un traveled to Russia last week for a meeting with President Vladimir Putin. Ahead of the meeting US officials warned that the two leaders could strike a deal that would provide weapons for Moscow to use in its grueling war against Ukraine - and that could see sanction-hit Pyongyang gain access to vital Russian technology.

That has alarmed South Korea, a US treaty ally.

But little is known of what went on behind closed doors; the two sides held no press conference, issued no communique, and have not publicly announced any deals.

Kremlin spokesman Dmitry Peskov said the two leaders did not sign any agreements during their talks.

Still, the talks signaled closer relations between the two countries, both of which face international isolation - Russia for its invasion of Ukraine and North Korea for its nuclear weapons and ballistic missile program.

As the war drags on, Moscow is desperate for fresh supplies of ammunition - while North Korea ramps up its weapons testing program, eager to advance its nuclear ambitions.