North Korea has warned the US it will be in a "very grave situation," and accused South Korea of carrying out an "intolerable provocation" against Pyongyang in a series of statements issued on Sunday. The statements were reportedly the country’s response to the Biden administration’s policy review on North Korea.

Washington plans to go for a "calibrated, practical approach" that is different from the Trump administration's strategy of pursuing a grand bargain or the Obama administration's focus on "strategic patience."

Kwon Jong Gun, director general of the Department of US Affairs of the North’s Foreign Ministry, called the US approach as a “spurious signboard for covering up its hostile acts” against the Democratic People’s Republic of Korea, which is North Korea's official name, reported the Voice of America.

“Now that … the keynote of the US new DPRK policy has become clear, we will be compelled to press for corresponding measures, and with time the US will find itself in a very grave situation,” Kwon said.

“The US will face worse and worse crisis beyond control in the near future if it is set to approach the DPRK-US ties, still holding on the outdated policy from Cold War-minded perspective and viewpoint,” he added.

In another statement, the US was accused of engaging in "political chicanery" last week, when the State Department called North Korea "one of the most repressive and totalitarian states in the world," reported CNN.

North Korean leader Kim Jong-un's sister, Kim Yo Jong, also made remarks in a statement in which she warned South Korea would face consequences after North Korean defectors used balloons to send anti-North propaganda leaflets into North Korean territory.

Kim said that North Korea could not hide its displeasure over the "sordid acts" carried out by the defectors, who she referred to as "human waste" and "dirty human scum." "We regard the maneuvers committed by the human wastes in the south as a serious provocation against our state and will look into corresponding action," she said.

Meanwhile, Biden and his South Korean counterpart, Moon Jae-in, are expected to have a meeting in Washington later this month.

Joe Biden President Joe Biden prepares to sign a series of executive orders at the Resolute Desk in the Oval Office just hours after his inauguration Getty Images | Chip Somodevilla