When Donald Trump warned Iran on April 7 that “a whole civilisation will die tonight,” a European diplomat in Washington said his government wanted an urgent answer to a chilling question: Was the US president contemplating the use of a nuclear weapon?Across Europe and Asia, the concern went beyond whether Trump’s apocalyptic threat was real or bluster. One fear, the diplomat said, was that Russia could seize the moment to justify similar threats in Ukraine, triggering a nuclear crisis on two continents.European governments immediately sought reassurance through a traditional channel: the US State Department. But according to the diplomat, officials there gave an unsettling response: they didn’t know what Trump meant or what actions his words might portend.The previously unreported episode points to a historic breakdown in American diplomacy. At a moment when a uniquely unpredictable US president is rattling markets and capitals with dramatic pronouncements, governments around the world are scrambling for clarity, only to discover that their usual points of contact — at US embassies or inside Washington — are missing, mute or out of the loop. At least half of America’s 195 ambassadorial posts worldwide are now vacant.Margaret MacMillan, an Oxford University professor of international history, said the Trump administration is eroding America’s capacity to understand the world it operates in, raising the risk of global instability.“We’re not going to be able to use diplomacy as we have often done before: to build relationships, get agreements that benefit both sides, and avert and end wars.”The Trump administration rejects the notion of a breakdown, saying the changes have strengthened US diplomacy and streamlined decision-making. “The president has the right to determine who represents the American people and interests around the world,” said Tommy Pigott, a State Department spokesperson.This account of America’s diplomatic upheaval is based on interviews with more than 50 senior diplomats, White House officials and recently retired ambassadors, as well as dozens of foreign officials, diplomats and lawmakers across Europe and Asia.As America’s career diplomats are fired or sidelined, its allies are changing how they deal with Washington. Rather than rely on embassies or formal channels, foreign governments say they are rewiring their diplomacy around a small circle of people with direct access to the president, leaving many dependent on back channels to manage a superpower whose signals have grown erratic.Some US allies now believe the most effective response to a volatile president is to treat his rhetoric as background noise.That calculus was evident after Trump’s threat to annihilate Iran stoked fears of nuclear war. In response, officials in Britain, France and Germany drafted what one European diplomat called a “harsh” joint statement later that day.But they chose not to release it, deciding Trump’s language was bluster and a public rebuke could prompt him to continue the bombing. By evening, Trump had announced a two-week ceasefire with Iran.The British, French and German foreign ministries didn’t reply to requests for comment.The episode, also previously unreported, illustrates an approach many allies now follow: restraint over confrontation. But diplomats said that repeatedly discounting Trump’s threats is also dangerous because it might leave them unprepared when another crisis looms.More than a year into Trump’s second term, influence and information are increasingly flowing through a handful of envoys. Most prominent: Trump’s son-in-law Jared Kushner and the president’s longtime friend, real estate developer Steve Witkoff. Kushner has no formal government title and Witkoff no prior diplomatic experience. But some foreign governments now prioritize communications with them over official channels, Reuters found.Kushner and Witkoff did not respond to requests for comment.Other countries have cultivated their own unconventional lines into the White House. South Korean officials bypassed US trade negotiators to forge ties with White House Chief of Staff Susie Wiles — a person they felt could explain Trump’s true intentions as they fought back against his 25 per cent tariffs. And Japan found an unlikely intermediary in SoftBank founder Masayoshi Son — one of Trump’s golfing partners. US Secretary of State Marco Rubio looks on as he speaks to the press before his departure following a G7 Foreign Ministers’ meeting with partner countries before his departure at the Bourget airport in Le Bourget, outside Paris, France on March 27, 2026. —Reuters/File The State Department was an early target in Trump’s second term. In April 2025, Secretary of State Marco Rubio called it a “bloated” bureaucracy gripped by “radical political ideology” and announced a “comprehensive reorganisation plan.”The effort was foreshadowed in Project 2025, a policy blueprint published in 2023 by the Heritage Foundation, a right-wing think tank in Washington, DC. The plan called for a leaner State Department with more political appointees and the removal of career ambassadors deemed hostile to the administration.About 3,000 employees left the State Department last year, nearly half fired and the rest taking buyouts — a roughly 15pc cut to its US-based staff. Then, in December, Rubio ordered the unprecedented recall of about 30 ambassadors worldwide.Rubio promised last year that his overhaul would “empower the Department from the ground up, from the bureaus to the embassies.” But today, 109 of the 195 US ambassadorial posts worldwide are vacant, according to the American Foreign Service Association, the diplomats’ union.A White House official said the changes “have made our government more efficient and less bloated and more able to effectively execute the president’s foreign policy.”The new structure leaves Washington with fewer top diplomats on the ground in a major war zone. Five of the seven countries bordering Iran, and four of the six Gulf States, have no US ambassador.Many US embassies are now run by chargés d’affaires — diplomats who serve as acting heads — rather than Senate-confirmed ambassadors, which some countries regard as a diplomatic downgrade.Former US ambassadors and State Department officials said the reduced diplomatic presence contributed to a chaotic scramble to evacuate Americans from the region when Trump started the Iran war.“Those missions should all have ambassadors when you’re fighting a war,” said Barbara Leaf, a retired career diplomat who served as US ambassador to the United Arab Emirates under the first Trump administration and as assistant secretary of state for Near Eastern Affairs under President Joe Biden.“At a moment of crisis — and it’s an open-ended crisis — this administration has left these missions in a parlous state.”Pigott said US embassies have performed well during the Iran war and are “more than appropriately staffed.”Diplomatic purgeFor Bridget Brink, the fracture between the Trump administration and its far-flung diplomats was potentially a matter of life and death.Brink was the US ambassador to Kyiv when Trump returned to office. In March 2025, just days after Trump’s explosive encounter with Ukrainian President Volodymyr Zelenskiy at the White House, the US cut off military aid and intelligence sharing to Ukraine.The weapons included air defense munitions that helped protect not just Ukrainians but also US embassy personnel from Russian drones and missiles, Brink said.“I had 1,000 people, all civilians, on the ground,” Brink said in an interview. “And we were protected by Ukrainians using US and other equipment.”The halting of military aid came without warning, she said. “When we tried to find out why it was stopped, we got no answer.”Brink reached out to the Pentagon, the State Department and the White House — “everywhere that we could, because we were very concerned about what this meant not only for Ukrainians but also for our own security.”The Pentagon did not respond to a Reuters request for comment on her account. A resident stands in her room in a dormitory hit by a Russian drone strike, amid Russia’s attack on Ukraine, in Odesa, Ukraine on April 30, 2026. —Reuters Brink said her staff worked behind the scenes to persuade the Trump administration to resume the aid, which it agreed to do on March 11. But she said she never received official confirmation of why the aid was halted in the first place.Layoffs at the National Security Council, which traditionally coordinates foreign and defense policy at the White House, further frayed relations between the Trump administration and its embassies. In 2025, Trump slashed the NSC from hundreds of people to just a few dozen.For months, NSC staff held no regular meetings and faced a de facto ban on holding interagency meetings on national security and foreign policy, according to three current and former US officials in Washington.The White House official said the NSC did not stop regular or interagency meetings but they were smaller and focused on Trump’s priorities.During that period, multiple officials said, staffers received little formal guidance about major topics such as the Ukraine war or Nato’s future. Instead, they scrutinised Trump’s Truth Social account for policy signals.Many NSC staffers kept Trump’s account open on a dedicated screen and responded quickly when he posted, the officials said.Under Biden, Brink had regularly joined NSC meetings to develop and coordinate complex wartime policy between Washington and the Kyiv embassy. Under Trump, those meetings stopped, Brink said.She was told instead to “just call people” — an ad hoc approach she described as inefficient and unworkable in a conflict zone where Russian attacks were routine.“We’re seven hours ahead and in the bunker almost every night.”The final straw, she said, was Trump’s policy of “appeasement” on Ukraine — seeking closer ties with President V