North Korea says US nuclear submarine at South Korea port posing grave threat: Report

Seoul: North Korea's defence ministry said on Tuesday the United States is again posing a grave security threat by sending a nuclear submarine to a South Korean port and its military forces are ready to take any action necessary, KCNA news agency reported.

The emergence of a US nuclear submarine in the Korean peninsula is a "clear expression of the US invariable hysteria for confrontation" against North Korea, an unnamed spokesperson for the North's defence ministry said in a statement.

"We express grave concern over the US dangerous hostile military act that can lead the acute military confrontation in the region around the Korean peninsula to an actual armed force conflict," the statement carried by KCNA news agency said.

Its armed forces will "unhesitatingly exercise the legitimate right to punish the provokers," it said, without elaborating.

South Korea's defence ministry said USS Alexandria submarine entered the Busan port on Monday for supplies and rest for its crew and that it will be a chance for the two countries' navies to promote exchange and combined defence posture.

Its military said it had no comment on the North Korean statement.

The US fast attack nuclear-powered submarine is part of the US Pacific Fleet armed with Tomahawk cruise missiles, according to the US navy.

North Korea routinely criticises the presence of US military assets and joint drills by US and South Korean forces. On Sunday, it warned of "undesirable consequences" criticising a series of exercises conducted by the allies.

The North's defence ministry spokesperson did not mention separate live-fire drills conducted jointly by South Korean and US armies at a firing range south of the militarised Korean border since last week.

The North has stepped up aggressive rhetoric since Donald Trump took office last month for his second presidency despite his comments suggesting he would reach out to North Korean leader Kim Jong Un for direct dialogue.