North Korea has fired two ballistic missiles eastward, in apparent reaction to the arrival of a US nuclear-powered submarine at a South Korean naval base.

South Korean and Japanese media reported the launch on Monday, saying the missiles flew about 400 kilometers (248 miles) before falling into the East Sea, also known as the Sea of Japan between the Korean peninsula and Japan.

The missiles were fired from an area near Pyongyang, South Korea's Joint Chiefs of Staff was quoted by the media as saying.

The US military said in a Monday statement that the launches posed no immediate threat to US personnel and territory or to US allies.

Korean relations at low point

The twin missile launch comes at a particularly low point in relations between the Korean neighbors. Seoul and Washington have been engaged in several joint security activities in an effort to counter the North Korean threats.

Their movements have angered Pyongyang. Last week, the US sent a nuclear-powered submarine to South Korea, for the first time since the 1980s. Pyongyang swiftly responded with a similar twin missile launch.

The launch also comes ahead of the anniversary of the 1953 armistice agreement that ended hostilites between the North and South, however the neighboring states are techically still at war, without a peace treaty ever having been signed.

North Korea celebrates the day as a victory, and is hosting this year Chinese dignitaries. This will be the first foreign visit to the country since its pandemic border closure.