John Bolton doesn’t do free trade. He does regime change in countries such as North Korea, Venezuela and Cuba. He does military interventions, notoriously in Afghanistan in 2001, Iraq in 2003 and Libya in 2011. He does punitive sanctions and embargoes. He does spite.

Bolton’s speciality is tearing up multilateral agreements, such as the Iran nuclear deal and the Paris climate accord, which he claims undermine US national sovereignty. For the same reason, he reviles the very idea of the UN, international law and the international criminal court (ICC).

So when Bolton, whose actual job is national security adviser to Donald Trump, came to London this week to meet Boris Johnson and senior ministers, the real focus of his visit, despite the Whitehall briefings, was not on a post-Brexit bilateral trade deal. It was on regime change in the UK. Bolton, a lifelong neoconservative ideologue, Muslim-baiting thinktanker and erstwhile Fox News commentator, does not give a hormone-filled sausage or chlorine-rinsed chicken wing for a free trade pact, fair or otherwise. Midwest wheat and soya exports are not his thing. What Bolton really does care about is exploiting the UK’s recent governmental upheaval, which almost anywhere else would be described as a rightwing coup, to America’s, and Trump’s, advantage. In short, the former colonies are out to colonise the UK.

Supposed American trade concessions will be tied to extraneous US foreign policy objectives

Bolton has three main aims. The first is purely transactional, in keeping with the Trump administration’s arm-twisting style. Although he says the US is content to wait until after Brexit on 31 October before pressing its demands, it’s already pretty clear what they will be. If Johnson wants a quickie sectoral trade deal on, say, the car industry, then Bolton’s price could be the UK’s withdrawal from the hard-won, US-trashed 2015 Iran nuclear agreement and the abandonment of fellow signatories France and Germany. In truth, Johnson and Dominic Raab, his neophyte foreign secretary, are already halfway down this road, having agreed to join a US-led maritime force in the Gulf rather than support a Europe-wide initiative initially proposed by Jeremy Hunt.

This U-turn is rightly seen in Tehran as evidence that the UK is falling in behind the aggressive, failing Trump-Bolton “maximum pressure” campaign. The risk of war with Iran is acute. The costs would be incalculable. But Brexit Britain, it seems, can be bought – a nation of shopkeepers after all, and mercenary to boot.

Other supposed American trade concessions will be similarly tied to extraneous US foreign policy objectives, although there will be a face-saving pretence that this is not so. In the name of helping “our British friends”, the US will seek support in ostracising China’s Huawei telecoms giant and, maybe, backing for its trade war with Beijing. The list of politely framed, slightly menacing American “requests” could go on and on. How about British acquiescence in Israel’s proposed, Trump-backed annexation of West Bank settlements, in defiance of UN resolutions hitherto backed by London? That could be seen as helpful, even necessary, in the UK’s new world of weakness.

Bolton’s enthusiasm for the “incredibly valuable” role that an “independent” UK could play in Nato, a regular target of Trump’s anti-European spleen, suggests an ever-greater degree of subservience. Will the price of market access soon include uncritical support for Trump’s renewed nuclear arms race with Russia and China, now he has scrapped the intermediate nuclear forces (INF) treaty? And whatever you do, chaps, don’t mention the words “climate crisis”. That sends Trump nuts.

The dire prospect raised by Bolton’s gleeful, hopefully premature Whitehall victory tour is one of the UK’s foreign and security policy outsourced to Washington, subordinated to the Trump-Bolton global agenda, and in hock to rightwing nationalist-populist ideology. Brexiteers promised a return of sovereignty. What’s coming is a sellout – a fire sale at the altar of America First.

Bolton’s second aim is to drive a wedge between the UK and Europe, and then use it as a sort of Afghan war-style forward operating base from which to disrupt, subvert and weaken the EU, whose very existence offends him. Throughout the Brexit negotiations, the official UK position has always been that whatever future EU trading relationship emerged, close cooperation on foreign and security policy would be maintained wherever possible. Yet that sort of continuity doesn’t suit Bolton’s purposes. For him, regime change means root-and-branch destruction of the status quo. If the UK, ever more beholden to the US for its daily bread, can be used to foil Emmanuel Macron’s ideas about integrated European defence, or undermine EU regulations covering digital multinationals, so much the better.

On this trajectory, the UK’s new best friends in Europe will not be Angela Merkel or Donald Tusk but Trump’s far-right chums, Hungary’s Viktor Orbán and Italy’s Matteo Salvini.

Freed from EU shackles, the UK, Bolton said, “will be pursuing UK national interests as it sees them”. For UK in that sentence, read US-approved. The UK will not even enjoy the equivalent position of one of the 50 US states, whose rights are protected by the federal constitution. On offer, if and when Johnson caves, is the status of mere satrapy – a tame, timid outpost of the American empire.

For this is the third Bolton aim: to enlist a radically repurposed and realigned UK in pursuit of his singular vision of American global hegemony, of the truly exceptional nation whose power and dominion know no limits and whose enemies quail before its unrivalled might. In Bolton’s imperious worldview, the pre-eminent, muscular and righteous US republic rises above all others, sustained by the ultra-conservative, libertarian, populist-nationalist preconceptions and prejudices that only those with commensurately tiny minds can seriously entertain.

Never mind that the shining city on a hill is now “an ugly pile of rubble”, as the US commentator, Maureen Dowd, sadly noted at the weekend. This is the recycled project for the new American century to which Johnson and his blindly buccaneering Brexiteers, trading time-honoured principles for quick bucks, are about to sign up. It will not make us prosperous or safe. It will make us ashamed.

• Simon Tisdall is a foreign affairs commentator