Britain’s stormy general election campaign has not focused much on foreign policy issues or the country’s role in the wider world, though it has of course been dominated by Brexit and the economic implications of leaving the European Union after 45 years of membership.

Still, last week’s Nato summit near London was a vivid reminder of the fractious and turbulent times we live in. Boris Johnson, the Conservative prime minister, was photographed at a Buckingham Palace reception laughing along with France’s Emmanuel Macron and Canada’s Justin Trudeau about the “jaw-dropping” behaviour of Donald Trump, who occupied centre-stage at the meeting of the Atlantic Alliance on its 70th anniversary.

Johnson had feared above all that the ever-unpredictable American president would say something that might affect the outcome of the December 12 election – especially about discussions over the highly sensitive issue of whether Britain’s revered National Health Service might form part of a post-Brexit UK trade deal with the US. Trump insisted, to audible sighs of relief in 10 Downing Street, that this was not so.

Macron had warned in advance that Nato was “brain-dead” because of its inability to deal with Vladmir Putin’s Russia. He was angry too over Trump’s “green light” to Turkey to mount an offensive into northern Syria against the Kurdish fighters who had spearheaded the defeat of Isis – without consulting other allies.

And the weekend before the summit a convicted Islamist extremist killed two young people in a knife attack on London Bridge in the heart of the capital – a bleak example of mounting concerns about radicalization and terrorism.

If Britain does end up leaving the EU, Nato will matter even more than before. “Ultimately, keeping terror off our streets and deepening our security cooperation with our Nato partners are two sides of the same coin,” commented the foreign secretary, Dominic Raab.

In recent days there have been other disturbing observations about the implications of leaving. Donald Tusk, the outgoing president of the European Council, described Brexit as “the real end of the British Empire” and warned that if it happened then the UK would be relegated to a second-rate global player. Later he described Brexit as “one of the most spectacular mistakes” in EU history after a campaign marked by “an unprecedented readiness to lie.”

Ahead of the 2016 referendum Brexiteers, including Johnson, described their vision as a way to “seize back control” from Brussels and forge a path to a “Global Britain.” Those views were challenged at the time by the Remain camp. But evidence that has accumulated since then suggests neither ambition is achievable.

Analysts argue that one option is for Britain to fall back on bilateral relations with individual countries, especially the “big five” of France, Germany, Italy, Poland and Spain, though that would not bring automatic access to collective, members-only, EU consultations.

The “Global Britain” concept is associated with the Anglosphere – especially the “Five Eyes” intelligence group of Australia, Canada, New Zealand, the UK, and the US – perhaps extending to the 53-member Commonwealth. But that geographically-dispersed virtual community is no substitute for full membership of a highly successful regional organisation that is also the largest single market on earth.

In an increasingly inter-connected world Britain is no longer uniquely qualified to act as hub – especially if it chooses to detach itself from its own immediate neighbourhood. It is also struggling to find the resources to support ambitious foreign and defence policies given the chaos of the past three years. The old claim about the “special relationship” with the US – and about serving as a bridge between America and Europe – is tired and unconvincing.

It is true that in the Middle East Britain has maintained its support for the 2015 nuclear agreement with Iran, along with the EU, despite Trump’s abandonment of the deal. The UK also denounced the US decision to recognise Jerusalem as Israel’s capital and its announcement that Israeli settlements in the occupied Palestinian territories were not in fact illegal. But it is legitimate to ask if those policies will survive Brexit.

And if the biggest challenge facing the world in the coming decades (as Nato leaders agreed) is the inexorable rise of China as an economic and military power, then how will “Global Britain” deal with that? The US has already applied pressure to ensure security of communications, including new 5G mobile phone networks, and wants allies to ban equipment from the world’s biggest telecoms manufacturer, the Chinese firm Huawei. Johnson insisted at the summit that he would not compromise Britain's national security over whether to give the telecoms giant a role in building the UK's 5G network. It was thus amusing to see, just the next day, when he gave another TV interview, that he took a selfie with the programme’s presenters with his smartphone and posted it on Instagram. That detail too, generated scornful headlines, as the phone turned out to be a Huawei.

Ian is a former Middle East editor, diplomatic editor and European editor for the Guardian newspaper. In recent years he has reported and commented extensively on the Arab uprisings and their aftermath in Syria, Libya and Egypt, along with frequent visits to Iran, the Gulf and across the MENA region. His latest book, a new history of the Palestine–Israel conflict, was published in 2017 to mark the centenary of the Balfour Declaration and the 50th anniversary of the 1967 war. He has an MA in history and social and political science from the University of Cambridge and a PhD in government from LSE. Ian has written for the Economist, the Washington Post and many other publications, and is a regular commentator on TV and radio on Middle Eastern and international affairs. He wrote the introduction to The Arab Spring: Revolution, Rebellion and a New World Order (Guardian Books, 2012); Israel's Secret Wars (Grove Press, 1991), Zionism and the Arabs, 1936–1939 (Taylor & Francis, 1986, 2015); and contributed to the Encyclopedia of the Modern Middle East and North Africa (Macmillan Library Reference, 2004). His most recent book is Enemies and Neighbours: Arabs and Jews in Palestine and Israel, 1917-2017 (Allen Lane, 2017).