Europe responded with a mixture of panic, disorientation and frantic steps to limit the damage after the resignation of US defence secretary, James Mattis.

Mattis’s decision to quit the administration came after Donald Trump confirmed he was ending all US military operations in Syria. He is also reportedly planning to halve the US troop presence in Afghanistan.

The resignation deprives Europe of one of its most reliable interlocutors and a firm supporter of the Nato transatlantic alliance. It is seen in Europe as an alarming symbol of Trump’s determination to take personal charge of foreign policy, and the pointed reference in his resignation letter to the need to treat allies with respect will echo across a continent alienated by the president’s insults and caprice. Above all, however, the resignation shows the depth of the foreign policy chasm between Trump and even mainstream Republicans on the US’s responsibilities to Europe and the Middle East.

James Mattis helped keep Trump in check. The world will miss him | Peter Beaumont Read more

British officials have described the outcome as deeply disturbing. The foreign Secretary, Jeremy Hunt spoke to the US Secretary of State, Mike Pompeo, on Thursday.

UK defence and foreign ministers, habitually inclined to keep differences with the US out of public sight, openly criticised Trump’s decision. The Middle East minister, Alistair Burt, tweeted: “There are no vacuums in foreign policy, certainly not in the Middle East. In a fragile region every action is a catalyst for another. If allies cannot be relied upon, others are sought to take their place. Jim Mattis understood – vital any successor agrees.”

The tweet is a warning to the US that the Gulf states, as well as the Kurds, may deduce that the US pullout means their long-term interests may lie in allying with other more steadfast partners such as Russia or China. Russia has been increasingly active in the Middle East, and now seems certain to emerge as the victor that protected the Syrian president, Bashar al-Assad. Other Arab countries are preparing to recognise Assad as victor by sending diplomats to Damascus.

The focus of British officials is now damage limitation including persuading the Turks to delay its planned military action against the Kurds, and to gather details of the timetable for the US troop withdrawal.

The UK defence minister, Tobias Ellwood, praised Mattis as “trusted, respected and admired by friends and allies, as well as feared and revered by our foes”. He tweetedwitter: “The most impressive military mind I’ve had the honour to know. Jim my friend – our world will be less safe without you.”

Ellwood had previously clashed with Trump’s assessment that Islamic State had been defeated in Syria. “It had morphed into something else,” he said.

The UK ambassador to the UN and a former political director at the Foreign Office, Karen Pierce, also clashed with Trump, pointing out that the UK air force is currently active over Syria, and the job of defeating Isis was far from over.

Germany, the country that had most to benefit from an agreed political settlement in Syria in terms of returning refugees, also insisted that Isis remained a security threat.

“The IS has been pushed back, but the threat is not over. There is a danger that the consequences of [Trump’s] decision could hurt the fight against the IS and endanger what has been achieved,” the German foreign minister, Heiko Maas, said in a statement.

The sense of a transatlantic crisis spread across the European foreign policy establishment. The co-chair of the European council on foreign relations Carl Bildt tweeted: “A morning of alarm in Europe. Sec Def Mattis is the remaining strong bond across the Atlantic in the Trump administration. All the others are fragile at best or broken at worst.”

The French president, Emmanuel Macron, was discussing with allies whether a supported French presence could act as a temporary substitute for the departing US ground troops in Syria.

Attempts were also being made to discover from a chaotic Washington administration how quickly the 2,000 US troops in north-east Syria were leaving, and, separately, how quickly Turkish troops plan to go over the border into Syria to attack what Ankara regards as Kurdish terrorist havens under the instruction of the country’s president, Recep Tayyip Erdoğan.

The sense of anger, edging on defiance, at Trump’s decision was clearest in Paris. The French defence minister, Florence Parly, said on RTL radio: “We do not share the analyses that the territorial caliphate has been annihilated. It’s an extremely grave decision, and we think the job must be finished. While the territory controlled by the caliphate is no longer what it was in 2014 ... if it has been reduced to near nothing, there remains, however, a pocket where jihadists have bunkered down,” she said.

Parly also suggested that implementing the withdrawal of 2,000 US soldiers from Syria should be discussed by the allied coalition. “You can’t withdraw troops from one day to another,” she said.

Macron has invited two leaders of the Kurdish-dominated Syrian Democratic Forces (SDF) to Paris to discuss how to protect the Kurds from what may now be an attack either by Isis, Turkish forces or Syrian government forces.

“The two co-chairs of the Syrian Democratic Council (MSD) Riad Darar and Ilham Ahmed are expected in Paris,” said SDF’s representative Khaled Issa, referring to the political arm of the previously US-backed militia that has formed the backbone of the fight against Isis.

France has about 1,100 troops in Iraq and Syria, providing logistics, training and heavy artillery and air support. It has dozens of special forces, military advisers and some foreign ministry personnel in Syria.

Macron spoke to Trump on Tuesday night, diplomats said. “The military campaign against Islamic State continues,” the French army spokesman Patrik Steiger told a news conference. “At this stage, the announcement by the American president has no impact on France’s ongoing participation.”

Even if a European force in Syria to combat Isis and protect the Kurds proves unrealistic, underlining the lack of its independent military capability, European politicians were fuming at the manner of Trump’s decision-making. Neither the Syrian withdrawal nor the prospect of cutting troop numbers in Afghanistan were preceded by any serious consultation with his European allies, many of whom either have ground troops or air forces operating in both countries.

The former UK ambassador to Lebanon Tom Fletcher spoke of “storm clouds darkening”.

Guy Verhofstadt, the leader of the Liberal Democrat group in the European parliament, said: “A victory for Russia, Iran, Turkey, Turkish proxies & the Syrian regime. Unsurprisingly, it leaves Europeans more vulnerable – and shows how wrong it is that we do not have a defence force able to help stabilise our immediate neighbourhood.”