Former national security adviser John Bolton has suggested Donald Trump is bluffing about stopping North Korea from producing nuclear weapons in his most direct criticism of the president’s foreign policy yet.

Mr Bolton, who resigned from the Trump administration in September, accused Mr Trump of having more of a “rhetorical policy” on North Korea rather than a serious plan in an interview with the news website Axios.

“The idea that we are somehow exerting maximum pressure on North Korea is unfortunately just not true,” the former adviser said.

“We're now nearly three years into the administration with no visible progress towards getting North Korea to make the strategic decision to stop pursuing deliverable nuclear weapons.”

His comments come amid heightened tensions after a top North Korean official said the country would send a “Christmas gift” to the US in December.

Kim Jong-un: Power in pictures Show all 20 1 /20 Kim Jong-un: Power in pictures Kim Jong-un: Power in pictures Kim Jong-un rides a horse during snowfall in Mount Paektu in this image released by North Korea's Korean Central News Agency on 16 October 2019 Reuters Kim Jong-un: Power in pictures Kim Jong-un visits the newly built Pyongyang Orphans' Primary School on 2 February 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a women's company under Unit 5492 of the Korean People's Army in November 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects the test-fire of intercontinental ballistic missile Hwasong-14 at an undisclosed location in July 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un celebrates the successful test-fire of the intercontinental ballistic missile Hwasong-14 at an undisclosed location in July 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a potato at the Samjiyon Potato Factory in North Korea in October 2018 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un rides a horse through a forest in this image released by North Korea's Korean Central News Agency on 16 October 2019 EPA Kim Jong-un: Power in pictures Kim Jong-un inspects a block of frozen fish at a processing facility in North Korea in November 2018 Reuters Kim Jong-un: Power in pictures Kim Jong-un celebrates the succeful launch of a strategic submarine-launched ballistic missile in August 2016 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un shakes hands with Donald Trump as they meet for the first time at the Capella Hotel on Sentosa island in Singapore in June 2018 Reuters Kim Jong-un: Power in pictures Kim Jong-un and Donald Trump share a glance as they meet in the Demilitarised Zone in Panmunjon, Korea in June 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects mushrooms at Pyongyang Mushroom Farm AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects a super-large multiple rocket launcher ahead of a test in September 2019 Reuters Kim Jong-un: Power in pictures Kim Jong-un inspects an apple farm in South Hwanghae Province in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects an apple farm in South Hwanghae Province in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects dental wares at a newly built factory in June 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un visits Farm No 1116 in September 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un visits a motor factory in November 2017 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un rides a horse during snowfall in Mount Paektu in this image released by North Korea's Korean Central News Agency on 16 October 2019 AFP/Getty Kim Jong-un: Power in pictures Kim Jong-un inspects the Command of the Strategic Force of the Korean People's Army at an undisclosed location in August 2017 AFP/Getty

It is thought that Kim Jong-un is planning to adopt a hardline anti-US policy, which would take denuclearisation off the table and abandon negotiations, according to a CNN report.

Mr Bolton told Axios that if North Korea defies the US, the Trump administration should admit its policy has failed and take a tougher approach on Mr Kim’s leadership.

The former adviser said he does not believe the administration “really means it” when it promises to stop North Korea producing nuclear weapons that could hit the US or its allies.

If Mr Trump was serious about tackling North Korea, he “would be pursuing a different course,” Mr Bolton said.

Mr Bolton has previously advocated for regime change by force in North Korea and has been singled out for criticism by the country’s foreign ministry.

In May, a government spokesperson called Mr Bolton a “warmonger” in response to his criticism of North Korea’s missile tests.

Mr Trump claimed last year that there was “no longer a nuclear threat from North Korea” after a summit with Mr Kim.

However, talks have stalled since then and analysts believe North Korea has expanded its nuclear capabilities.

Stephen Biegun, the US deputy secretary of state, recently said it would be “most unhelpful in achieving a lasting peace on the Korean Peninsula” if North Korea followed through on its threat to test advanced weapons.