Korea's Kim visits nuclear subs as Putin hails 'invincible' bond

SEOUL:

North Korean leader Kim Jong Un visited a nuclear submarine factory and received a message from Russia's Vladimir Putin hailing the countries' "invincible friendship", Pyongyang's state media said Thursday.

North Korea and Russia have drawn closer since Moscow launched its full-scale invasion of Ukraine nearly four years ago, and Pyongyang has sent troops to fight for Russia.

In return, Russia is sending North Korea financial aid, military technology and food and energy supplies, analysts say.

The "heroic" efforts of North Korean soldiers in Russia's Kursk region "clearly proved the invincible friendship" between Moscow and Pyongyang, Putin said in a message to Kim, according to the Korean Central News Agency (KCNA).

Their work demonstrated the nations' "militant fraternity", Putin said in the message received by Pyongyang last week.

The provisions of the "historic treaty" the two leaders signed last year, which includes a mutual defence clause, had been fulfilled "thanks to our joint efforts", Putin wrote.

South Korean and Western intelligence agencies have estimated that the North has sent thousands of soldiers to Russia, primarily to Kursk, along with artillery shells, missiles and long-range rocket systems.

Around 2,000 troops have been killed and thousands more have been wounded, according to South Korean estimates.

North Korea acknowledged this month that its troops in Kursk had been assigned to clear mines and that some had died on deployment.

KCNA reported Putin's letter on the same day that it published details of Kim's undated recent visit to a manufacturing base for nuclear-powered submarines.

There, the North Korean leader vowed to counter the "threat" of South Korea producing its own such vessels.

US President Donald Trump has given the green light for South Korea to build "nuclear-powered attack submarines", though key details of the project remain uncertain.