Stryker McGuire, who lives in London, is a former editor at Newsweek and Bloomberg.

About six months after Britons voted in 2016 to leave the European Union, then-Foreign Secretary Boris Johnson gave a speech on his country’s putative new place in the world. “Brexit emphatically does not mean a Britain that turns in on herself,” he said. “We are not some bit part or spear-carrier on the world stage. We are a protagonist — a global Britain running a truly global foreign policy.”

Johnson, the prime mover behind Brexit, is now prime minister. When world leaders come together in Scotland for the Glasgow Climate Change Conference at the end of this month, he’ll have a chance to show whether his “Global Britain” ambition is for real. It’s going to be a tough sell.

Twenty-one months after officially leaving the E.U., Johnson’s Britain continues to search for its identity. It’s no longer part of the world’s second-largest consumer market. It’s nowhere near doing a trade deal with the No. 1 market, the United States. And for all of Johnson’s talk of a “buccaneering” Britain that would reinvent itself as a kind of Singapore-on-Thames, the post-Brexit United Kingdom has barely begun to do that — or even to nail down deals with other partners.

Militarily, Britain has traditionally sought to enhance its power by hitching itself to the United States. That’s not going so well either. President Biden’s abrupt withdrawal from Afghanistan this summer caught Johnson unaware and left Washington’s most important ally there looking like a bystander. In the House of Commons, Johnson’s predecessor as prime minister, fellow Conservative Theresa May, acidly asked him, “Where is Global Britain on the streets of Kabul?”

In March, the Johnson government published “Global Britain in a Competitive Age: the Integrated Review of Security, Defense, Development and Foreign Policy.” Though its importance has been somewhat lost in the fog of covid-19 and Brexit, the review is probably Britain’s most substantial strategic rethink since the Cold War.

The review’s central aspiration is that Britain should be “a soft power superpower.” There are valid historical reasons to make such a claim, but the Johnson government is already undermining some of them. Among other things, it has reduced foreign aid from 0.7 percent of gross domestic product to 0.5 percent, a reduction of more than £4 billion ($5.45 billion). But that’s just the beginning.

Among Britain’s soft-power strengths, the review cites first and foremost the BBC, “the most trusted broadcaster worldwide.” And yet Conservative politicians, including Johnson, have long waged war on the BBC. In early October, the Johnson cabinet member whose portfolio includes the media, Culture Secretary Nadine Dorries, said, “Will the BBC still be here in 10 years? I don’t know.”

Johnson is not the first prime minister to seek to elevate the U.K.'s global standing since the sun set on the British Empire. Former U.S. secretary of state Dean Acheson said in 1962 that Britain’s days as an independent world power were “about played out.” “Great Britain has lost an empire and has not yet found a role,” he said. (Ironically, Acheson prescribed joining the Common Market, precursor to the E.U., as the antidote to decline.)

Margaret Thatcher tapped into U.S. power by standing with her fellow Cold Warrior, Ronald Reagan. Tony Blair embraced what critics archly called a “51st state” strategy that locked Britain into America’s wars and, in the case of Iraq, backfired so spectacularly that London-Washington relations, though durable, have been strained ever since.

Now it’s Johnson’s turn, but he’s arguably “Global Britain’s” greatest enemy. Though he’s a genuinely charismatic politician, he makes it hard for all but his devotees to take him seriously. His serial prevarication is Trumpian in scale. He disdains detail. He relies on theatrical antics over substance.

A case in point is the Brexit Withdrawal Agreement’s Northern Ireland Protocol, which is meant to protect the 1998 Good Friday Agreement that has reduced sectarian violence in Northern Ireland (and, incidentally, is considered sacrosanct by the Biden administration). Johnson cynically negotiated the protocol prior to the 2019 election, which he then won in a landslide with the slogan “Get Brexit Done.”

It was clear even then that Johnson had no intention of honoring it because it established a border down the middle of the Irish Sea, leaving Northern Ireland sitting within the E.U. single market and causing havoc with trade. Ever since, Johnson has been trying to undo an international treaty he himself signed — undermining his credibility and Britain’s.

Of course, the pandemic has drained resources and delayed plans. But Britain urgently needs new ideas if it is to fulfill a new global destiny. It also needs a leader to match its ambitions. So far, at least, Johnson shows no sign of being that person.