"If you wish to sleep well..." - Kim Yo Jong warns Joe Biden! - What happened?

North Korean leader Kim Jong Un's influential sister Kim Yo Jong has warned the United States against actions that could make it "lose sleep", state media reported on Tuesday, as top Joe Biden administration officials began a visit to key allies Tokyo and Seoul.

Pentagon chief Lloyd Austin and Secretary of State Antony Blinken arrived in Japan on Monday on their first overseas trip with a view to rallying military alliances as a bulwark against China and cementing a united front against the nuclear-armed North.

The statement by Kim Yo Jong was Pyongyang's first explicit reference to the new president in Washington.

The United States and South Korea began joint military exercises last week and Pyongyang's official Rodong Sinmun newspaper carried a statement from Kim Yo Jong offering "a word of advice to the new administration of the United States that is struggling to spread the smell of gunpowder on our land".

"If you wish to sleep well for the next four years, it would be better not to create work from the start that will make you lose sleep," she was quoted as saying.