North Korea yesterday threatened a further military build-up in response to Joe Biden's condemnation of this week's missile launches, a weapons test that marked Pyongyang's first substantive provocation since the US president took office.  

The nuclear-armed North has a long history of using weapons tests to ramp up tensions, in a carefully calibrated process to try to forward its objectives.

Following the launch, Biden labelled the test a violation of UN resolutions and advised the isolated state against ramping up military testing, warning that "there will be responses if they choose to escalate."

Ri Pyong Chol, a leading official in North Korea's missile programme who supervised the test, said the president's comments had revealed his "deep-seated hostility" to the regime.

"Such remarks from the US president are an undisguised encroachment on our state's right to self-defence and provocation to it," Ri said in a statement published by state media outlet KCNA.

"If the US continues with its thoughtless remarks without thinking of the consequences, it may be faced with something that is not good," he added, warning that North Korea was prepared to "continue to increase our most thoroughgoing and overwhelming military power."

The comments came at a time when Washington is in the final stages of a policy review on North Korea, with signals of a firm line on denuclearisation, sanctions and human rights.

Leif-Eric Easley, a professor at Ewha University in Seoul, said Ri's remarks were "essentially a threat that North Korea will respond to the US policy review with more tests".

Pyongyang has made rapid progress in its capabilities under leader Kim Jong Un, testing missiles capable of reaching the entire continental United States as tensions mounted in 2017.

North Korea has reported that the Thursday launch, its first substantive affront since Biden came to office, was a test of a new "tactical guided projectile" with a solid-fuel engine.

Japanese Prime Minister Yoshihide Suga called the two weapons launched from North Korea's east coast ballistic missiles, which it is banned from developing under UN Security Council resolutions.

A UN sanctions committee focused on nuclear-armed North Korea has asked its experts to investigate the test and European members of the Security Council have requested an urgent meeting to discuss North Korea.

The North is already under multiple sets of international sanctions for its banned nuclear weapons and ballistic missile programmes.