North Korean leader Kim Jong Un's influential sister slammed the US and South Korea on Tuesday, state media reported, as the new US secretaries of state and defence began a visit to Tokyo and Seoul.
The US and South 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 from across the ocean".
"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 said.
It is the first explicit reference by the nuclear-armed North to a new president in Washington, more than four months after Joe Biden was elected to replace Donald Trump -- although it still did not mention the Democrat by name.
Trump's unorthodox approach to foreign policy saw him trade insults and threats of war with Kim Jong Un before an extraordinary diplomatic bromance that saw a series of summits.
But ultimately the relationship made no progress towards the denuclearisation of the North, which is under multiple international sanctions for its banned weapons programmes.
The talks process was brokered by the South's President Moon Jae-in but relations between Seoul and Pyongyang have been in the deep freeze since Kim and Trump's summit in Hanoi collapsed in February 2019.
Kim Yo Jong is a trusted adviser to her brother and was a key voice when inter-Korean tensions mounted last year, culminating in the North blowing up a liaison office on its side of the border.
Seoul and Washington are treaty allies, with the US stationing around 28,500 troops in the South to defend it against its neighbour, and they began computer-simulated joint military exercises last week.
The North always condemns such drills as preparations for invasion, and in her statement, Kim Yo Jong said: "The South Korean government yet again chose the 'March of War', the 'March of Crisis' rather than a 'warm March'' before all the people."
"It will not be easy for the warm spring days of three years ago to come back if the South Korean government follows whatever instructions of its master," she added, threatening to scrap a North-South military agreement if Seoul acts "more provocatively".