‘Highly unusual’ North Korean submarine activity spotted by US military

The US military has detected “highly unusual and unprecedented levels” of North Korean submarine activity in the wake of that country’s second intercontinental ballistic missile launch late last week, CNN said on Monday.

Citing a defence official, the television news channel reported that North Korea on Sunday carried out a trial of the missile component that is critical to developing submarine launch capabilities.

The “ejection test”, carried out on Sunday on land at the Sinpo Naval Shipyard, was the third this month and fourth this year. It came after North Korea test-launched its second ICBM late Friday night.

According to the report, an ejection test examines a missile’s “cold-launch system”, which uses high pressure steam to propel a missile out of the launch canister into the air before its engines ignite. That helps prevent flames and heat from the engine from damaging either the submarine, submersible barge or any nearby equipment used to launch the missile.

The ejection test took place amid the backdrop of increased activity by North Korea’s submarine fleet, believed to comprise about 70 subs though most are quite old and likely cannot fire missiles.

Earlier this month, for example, North Korea sent a diesel-powered Romeo-class sub on an unprecedented patrol in waters off the coast of Japan, CNN said, citing US defence officials.