The world can afford a sigh of relief after news that North Korea’s latest attempt to launch a long-range missile has once again led to embarrassing failure. With Mike Pence, the US vice-president, in Seoul, could this be a moment for some realpolitik from the United States?

For as bizarre as it may seem given Donald Trump’s unpredictability and disturbing lurches into infantilism – displayed in his brinkmanship with the equally volatile North Korean dictator, Kim Jong-un – he could just as easily help bring about peace as he could thermonuclear war.

The world has been on tenterhooks this weekend as North Korea ramped up its bloodcurdling rhetoric threatening a nuclear response to any American-led preventive attack on its ballistic missile programme. In the course of a few days Trump has gone from tweeting that “North Korea is looking for trouble”, and if China “does not decide to help” the US “will solve the problem without them”, to sheepishly acknowledging that the North Korean imbroglio was more complex than he had first realised.

Who can keep up with Trump? Perhaps he can't even keep up with himself

That should come as no surprise. Over the past few weeks his administration has gone from making belligerent remarks about China’s activities in the South China Sea to conjuring up visions of a calamitous meeting between President Xi and himself, before finally painting an endearing picture of enduring friendship between the pair. Trump’s policy towards Russia and to intervention in Syria has undergone a similar 180-degree turn, with the blustering British foreign secretary, Boris Johnson, meekly acquiescing at each twist and turn. Who can keep up with Trump? Perhaps he can’t even keep up with himself.

Once this particular crisis on the Korean peninsula has, hopefully, calmed down, Trump could just as easily become a man of peace, taking a leaf from Richard Nixon’s famous meeting with Mao Zedong that normalised relations between the two countries in 1972. Could he tear up all that has gone before and eventually sign a final peace agreement with North Korea that would have, at its heart, an agreement to make the Korean peninsula nuclear free? It is a possibility, just not one that the American military is prepared to countenance so long as North Korea continues with its nuclear programme.

I have recently learned that the Trump administration’s policy review for North Korea is essentially complete. A team of experts led by the national security council has looked at every eventuality, including the redeployment in South Korea of nuclear weapons, which were removed in 1992. According to Glyn Ford, the former European parliamentarian and North Korea expert, the likelihood is that this US administration’s patience will finally run out after another couple of nuclear tests. The fact that North Korea triggered a further missile test to coincide with the 105th anniversary of the birth of Kim Il-sung, the state’s founder and Kim Jong-un’s grandfather, suggests that China’s ability to pressure the regime is limited.

Richard Nixon shakes hands with Mao Zedong during Nixon’s historic trip to China in 1972. Photograph: AP

Trump’s boast to a TV host that he had informed President Xi of his Tomahawk missile attack on a Syrian airbase as they shared chocolate cake was surreal theatre at its most grotesque. But it was a message designed explicitly with North Korea in mind, as was his bunker-busting bomb in Afghanistan. The Chinese are intensely nervous and irritated by the behaviour of the formerly useful buffer state that is now a source of potential nuclear conflict and waves of refugees.

Ford, who has been engaged in almost continuous low-level shuttle diplomacy for nearly two decades between Pyongyang, Seoul and Beijing, is clear that the United States will simply not tolerate North Korea becoming a de facto nuclear state. He believes that the window of opportunity could be as little as six months before the US will strike. The Pentagon will have mulled over preventive strikes against the North Korean nuclear programme, but has been facing the horrifying prospect of an artillery response that could lead to the South Korean capital, Seoul, being consumed in what Kim Jong-il – Kim Jong-un’s father – described in 2011 as a “sea of fire”.

Ford also asks the questions: “What have we learned from Iraq, and why is the UN security council not taking a lead in getting the United States, China and North Korea to the negotiating table?” The answer may be that thus far the Trump administration has no intention of going to the United Nations, an organisation that Trump believes is for people to go to “just to have a good time”. As far as Trump is concerned, multilateralism is for the birds.

A window of hope could open after South Korea’s 9 May elections and a fresh new administration with a mandate to seek a solution and avoid an unthinkable military conflict. South Korea’s likely new progressive government could move to reopen the jointly run Kaesong industrial complex in the border area with North Korea. This could be a heaven-sent opportunity for the former UN secretary general Ban Ki-moon, now back in South Korea, to play a key role as peacemaker.

And Britain could begin to play a far more positive and independent role. But this would require Boris Johnson to work more closely with his opposite numbers in Europe and to not make foreign policy on the hoof.

It would also require Michael Fallon, the defence secretary, to halt the pretence that Britain is somehow an equal military player with the United States. He would have to realise that the only real power Britain has is to make it clear that it will not be part of any planned “coalition of the willing” acting without the backing of the UN security council in any future US military venture in Korea.

In fact, Britain could begin to demonstrate its vaunted new independence by taking a clear lead, proposing its own security council resolution demanding new UN-sponsored talks tasked with achieving a final peace agreement on the Korean peninsula.