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Senior British officers serving at the Pentagon have been briefed that one of the new administration’s top priorities will be to “sweep away” plans championed by Germany and France. ”We have been told quite clearly that, in an environment in which the political temperature in Eastern Europe is high and fiscal pressure on budgets is increasing, there can only be one joint force and that is Nato,” he said.

GETTY Donald Trump has told Brussels to ditch plans for an EU Army

“Senior US officers directing future strategy want to see more delivery from European nations. There is grave concern about the intent and growing talk of an EU Army, which appears to draw resources away from the Alliance.” Burden sharing by Europe is expected feature highly during Theresa May’s visit with Trump next month, though Britain is one of only five members meeting spending targets. Despite comments by President Trump calling Nato “obsolete”, new US defence secretary Gen James Mattis affirmed America’s commitment to the Alliance – and reinforced concerns against Russia.

“We have a long list of times we’ve tried to engage positively with Russia. We have a relatively short list of successes in that regard,” he told Congress on Friday.

We have a long list of times we’ve tried to engage positively with Russia US defence secretary Gen James Mattis

While European defence spending is the primary concern, insiders warned that Trump would also be gauging Europe’s “boots on the ground” commitments. The US currently fields six Brigades in Europe, including the newly arrived 3rd Armour Brigade which boasts hundreds of armoured vehicles, including 87 tanks, and 3,500 troops to boost Nato’s efforts to deter Russia in Eastern Europe. Of Europe’s Nato members, only Britain and France have put themselves forward to lead three of its remaining four battalions.

GETTY The new US President threatened to cut Nato funding if the block does not abandoned its plans

Donald Trump's historic inauguration in pictures Mon, January 23, 2017 The inauguration of Donald Trump as the 45th President of the United States marked commencement of the four-year term as President and Mike Pence as Vice President. Play slideshow AP 1 of 40 President Donald Trump waves as he walks with first lady Melania Trump and son Barron during the inauguration parade.

“President Trump is a numbers man. Defence spending is one thing, but when he meets with Nato chiefs in Brussels later this year, he will do the math: the US is deploying almost six battalions in Europe. How does this stack with Europe’s commitment? The US and Germany are playing their part but what about the rest?”, said another source close to the administration. He said that Trump’s use of the word “obsolete” to describe Nato had been misinterpreted, adding: “He means that Nato must adapt to 21st Century challenges, including a counter–terror role. “President Trump realises that, for just one per cent of the US defence budget, he can call upon 27 nations to stand up with it around the world.

“Europe supplied 40,00 troops to Afghanistan. That equates to 120,000 in real terms because for each soldier, two are in rotation. That's 120,000 US troops who didn't have to go to battle.” During his campaign Trump pledged tens of thousands of new US troops, dozens of ships and hundreds of warplanes, plans would cost almost $100 billion more than the Pentagon has currently budgeted for Trump’s first term. Rudi Giulliani, a key figure in Trump’s campaign, said the President was adopting a Reagan-like “peace through strength” strategy. The former New York Mayor, who had dinner with Trump on Wednesday, said: “He believes that of the last 30 presidents of the last 50 -60 years, the most successful was Ronald Reagan, because he negotiated from strength and, lo and behold, won the cold war without firing a shot.”

GETTY Gen James Mattis affirmed America’s commitment to Nato

The controversial 1000-strong Euro Corps was formed in 1993 and is spearheaded by a German- Franco brigade of troops. It provided HQ staff for operations in Afghanistan in 2004 and currently supports an EU maritime operation against pirates off Somalia. Directed by Brussels it is manned by 10 EU member states and Turkey. While in the EU, Britain used its influence to block its expansion. Brexit was met with the immediate publication of plans to build a military new headquarters, as the EU scrambled to reinforce the project’s identity. Separately, Germany’s defence white paper revealed its own ambitions to lead a pan-European force. The moves have caused concern in the Trump camp.

GETTY The US 3rd Armour Brigade recently arrived in Europe to deter Russia in the east