North Korea said on Monday that the United States' hostile policy remained unchanged and vowed to continue strengthening its nuclear force, rejecting repeated US calls for its denuclearisation, according to state media KCNA.

A foreign ministry spokesperson accused Washington of maintaining a confrontational stance through its commitment to the "complete denuclearisation" of North Korea, criticism of the country's human rights record and planned joint military exercises with South Korea and Japan.

"The Trump administration has thus fully reconfirmed its invariable hostile policy to wantonly violate the sovereignty, political system and security interests of the DPRK," the spokesperson said.

The spokesperson said North Korea's nuclear weapons were "an absolute guarantee for defending its sovereignty" and that its nuclear status would not be weakened by repeated US denuclearisation demands. The spokesperson also said expecting any easing of regional tensions was "pointless," and that there is "no change" in North Korea's policy toward the US.

The statement came after US President Donald Trump this month ordered a major scaling back of the annual Ulchi Freedom Shield exercises between the United States and South Korea. Trump cited his "very good relationship" with North Korean leader Kim Jong Un and said the drills were costly and sent an unnecessarily hostile signal to Pyongyang. Trump has been seeking a new summit with Kim, whom he met three times in 2018 and 2019.

Despite the drills reduction, Kim Yo Jong, the North Korean leader's sister, said this month the exercises remained provocative and aggressive even if their scale and duration were reduced.

Separately, the US, South Korea and Japan are due to hold the Freedom Edge exercise, which is intended to improve coordination against nuclear and missile threats, from September 7 to 11, according to Seoul's military. North Korea has repeatedly denounced the trilateral drill as a threat to regional security.

Recent weeks have seen a dramatic shift in US-North Korea relations, with Trump expressing a desire to meet Kim. However, North Korea responded coolly and showed little interest.

Last week, North Korea condemned the US decision to approve the sale of missiles and related equipment to South Korea and vowed to take a strong response. The North Korean statement said it is aware of such threats and will have a "serious, immediate and powerful response to hostile acts in different spheres."