Just days after menacing North Korea with the huge US nuclear arsenal, US President Donald Trump suggested he would be willing to talk to North Korean leader Kim Jong-un, under the right circumstances. The first official talks between the two Koreas in two years are due to take place tomorrow, after Kim’s offer to send a team to the Winter Olympics next month in South Korea.

Speaking to reporters at Camp David on Saturday, Trump backed tomorrow’s talks. “I hope it works out,” he said. “I very much want to see it work out between the two countries.” He declared that the meeting was “a big start” and again bragged that he was responsible for bringing it about. “[If] I weren’t involved, they wouldn’t be talking at all right now,” Trump said.

Asked whether he would be prepared to talk to Kim, Trump replied: “Sure, I always believe in talking... Absolutely I would do that. I don’t have a problem with that at all.” At the same time, he insisted his administration would maintain “a very firm stance” and he was “not messing around. Not even a little bit.”

Last week, however, Trump openly threatened North Korea with nuclear annihilation. After Kim, in his New Year’s speech, warned the US that he had a nuclear button on his desk, Trump tweeted that his own nuclear button was “a much bigger & more powerful one, and my Button works!” Trump has at his disposal thousands of nuclear warheads with sophisticated delivery systems that completely dwarf North Korea’s limited nuclear arsenal.

Trump’s reckless tweets only inflame what is already an extremely tense situation in which the US has repeatedly threatened North Korea with military attack if it fails to abandon its nuclear and missile programs. Moreover, rather than encouraging talks, the comments undermine the possibility of a peaceful end to the present confrontation.

Senior Trump officials yesterday defended the president’s erratic comments after criticism in the media and Congress fed into the political firestorm surrounding the White House over Trump’s competence to hold the top job.

Speaking on the ABC’s “This Week” program, US ambassador to the UN, Nikki Haley, declared that Trump’s incendiary “nuclear button” tweet would “keep [North Korean leader] Kim on his toes” and remind him that in the event of nuclear war “it’s not us that’s going to be destroyed, it’s you.”

Asked if such remarks hurt US credibility with its allies in Asia, Haley said: “I know it’s something that makes people nervous but if we didn’t do it, we would be in a more dangerous [situation].” She dismissed criticism, including from congressional Republicans such as Cory Gardner and John Cornyn, that the tweet was reckless, saying “everyone is going to have their opinion.”

The US ambassador played down any suggestion of a significant breakthrough at tomorrow’s talks between the two Koreas, saying: “I think they’re going to talk about the Olympics. It’s not my understanding that they’re going to talk about anything further.”

Haley emphasised that talks between Washington and Pyongyang would take place only if North Korea agreed in advance to US demands to denuclearise. “What he [Trump] has basically said is yes, there could be a time where we talk to North Korea but a lot of things have to happen before that actually takes place. They have to stop testing. They have to be willing to talk about banning their nuclear weapons. Those things have to happen.”

Speaking on CBS’s “Face the Nation,” CIA Director Mike Pompeo indicated that time was running out rapidly for a peaceful end to the standoff with North Korea. He said Pyongyang was “a few months away” from “crossing the threshold to putting a US city at risk of nuclear attack,” but refused to be more specific.

Pompeo was sceptical that the talks between North and South Korea represented a positive step. “I hope that’s the case,” he said. “But past history would indicate that this is a feint, this is not likely to lead to any true change in his [Kim’s] strategic outlook. That is, he will continue to maintain his nuclear capability. And that the president has said is unacceptable.”

Trump himself publicly rebuked US Secretary of State Rex Tillerson in October, saying his diplomatic efforts to lay the basis for talks with North Korea were “a waste of time.” The president’s only concession has been to agree to delay major joint US-South Korean military exercises until after next month’s Winter Olympics.

The US military, however, has been honing its plans for war with North Korea over the past year and has conducted a succession of major military drills with South Korea to rehearse for such a conflict. Last month the Pentagon held a large-scale joint air exercise that included the latest US stealth fighters, as well as a special forces drill, to practise for a military intervention into North Korea.

These preparations are not just for conventional, but also for nuclear war. The Centres for Disease Control and Prevention (CDC) announced a special briefing on January 16 to advise federal, state and local governments on the work to be done in the event of a nuclear attack on the US.

The notice stated: “While a nuclear detonation is unlikely, it would have devastating results and there would be limited time to take critical protection steps. Despite the fear surrounding such an event, planning and preparation can lessen deaths and illness.”

Over the past week, former US Joint Chiefs of Staff chairman Mike Mullen and ex-Vice President Joe Biden both declared they believe the world is closer to a nuclear war with North Korea than ever before.