SEOUL (THE KOREA HERALD/ASIA NEWS NETWORK) - Tensions between the US and North Korea and between South and North Korea are heightening simultaneously.

The United States and the North swiftly entered a tense mode as Pyongyang condemned Washington's stance in its North Korea policy, of which the White House is said to have completed its review.

Inter-Korean ties were further strained as the North threatened the South with corresponding action for the recent release of anti-North Korean leaflets by a group of North Korean defectors.

It is hard to expect the situation to change in the near future.

Referring to threats from North Korea and Iran during his address to a joint session of the US Congress, President Joe Biden vowed to work closely with the country's allies to address the issue "through diplomacy and stern deterrence".

The basic direction of the new US administration's North Korea policy is to denuclearise North Korea step by step through diplomacy and negotiations while tightening sanctions.

Mr Biden is critical of former US president Donald Trump's approach of seeking a one-and-done big deal with his North Korean counterpart.

North Korea condemned the US harshly.

Citing Mr Biden's speech to Congress, Mr Kwon Jong Gun, director-general of the North Korean Foreign Ministry's US affairs department, said the US president "made a big blunder".

He warned that the US would "find itself in a very grave situation" and that North Korea would be compelled to press for corresponding measures.

In a separate statement, an unnamed spokesman for the North Korean Foreign Ministry reacted strongly to the US State Department's criticism of North Korea's human rights situation.

He accused Washington of pursuing a "hostile policy" against North Korea, "encroaching upon the North's sovereignty" and "insulting the dignity of the country's supreme leadership".

The spokesman said the criticism of North Korea's human rights situation is a provocation that shows the US is girding itself for an all-out showdown with North Korea and will be answered accordingly.

The North Korean statements came at a time when the US was wrapping up its policy on the North. They appear to be an attempt to strengthen Pyongyang's influence in its future relations with the US.

The mention of corresponding measures implies the possibility of provocations from North Korea.

That is a signal of an intention to provoke with nuclear weapons and missiles unless Washington eases sanctions or withdraws its strategic assets.

For decades, North Korea has raised tensions through provocations when it had difficulty getting what it wanted from the US.

With a sensitive situation unfurling between the US and North Korea, Ms Kim Yo Jong, a senior official in the North Korean government and sister of leader Kim Jong Un, criticised South Korea for failing to prevent defector activists from flying anti-North Korean leaflets.

She said the North would look into corresponding action.

Fighters for a Free North Korea, a vocal group of North Korean defectors, claimed last week that it had sent anti-Pyongyang leaflets on two occasions between April 25 and 29.

If confirmed, this would mark the first time anti-North Korean leaflets were sent across the border since a government ban on such activity took effect in late March.

Her condemnation evokes a memory of North Korea blowing up an inter-Korean joint liaison office in its border town in June last year, 12 days after she lashed out at South Korea for failing to stop the leafleting.

She threatened to retaliate this time, too. If South Korea submits to her threat, North Korea will try to gain the upper hand over the South. The South should deal sternly with the North's threats.

Mr Kim believes that nuclear weapons are the last bastion for the preservation of his power. This belief has never changed. The moment sanctions are eased, the leverage to move North Korea will lose strength.

The threat of corresponding action raises the possibility of North Korea mounting military provocations on the occasion of the May 21 South Korea-US summit.

Seoul and Washington must work closely not to be deceived by Pyongyang's provocation tactics. Under no circumstances should they take their eyes off the obvious goal of denuclearising the North completely.

• The Korea Herald is a member of The Straits Times media partner Asia News Network, an alliance of 23 news media organisations.