DONALD Trump has been told to remember who his friends are, ahead of a tense two-day Nato summit in Brussels.

As the US president prepared to board Air Force One, the European council president, Donald Tusk, delivered a rather blunt message: “Appreciate your allies. After all you don’t have that many.”

Speaking at an EU-Nato ceremony, Tusk added: “Dear President Trump, America does not have and will not have a better ally than Europe. Today Europe spends on defence many times more than Russia and as much as China. And I think you can have no doubt ... that this is an investment in common American defence and security which can’t be said with confidence about Russian and Chinese spending.”

Trump is due to visit the UK after the Nato summit.

He is expected to stay until next Monday when he will meet with Vladimir Putin in Finland.

Tusk added: “European troops have been fighting shoulder to shoulder with American soldiers in Afghanistan; 870 brave men and women sacrificed their lives, including 40 soldiers from my homeland, Poland.

“Dear Mr President, please remember about this tomorrow when we meet at the Nato summit, but above all when you meet president, Putin, in Helsinki. It is always worth knowing who is your strategic friend and who is your strategic problem.”

Answering questions on the White House lawn before he and First Lady Melania left Washington, Trump said the UK “certainly has a lot of things going on”.

“It’s going to be an interesting time in the UK and an interesting time at NATO,” Trump told reporters.

“We will work it out and all countries will be happy.

“So I have Nato, I have the UK – which is in somewhat turmoil.”

The US President added: “And I have Putin. Frankly, Putin may be the easiest of all.”

Earlier he had tweeted: “Getting ready to leave for Europe. First meeting – Nato. The U.S. is spending many times more than any other country in order to protect them. Not fair to the U.S. taxpayer. On top of that we lose $151 Billion on Trade with the European Union. Charge us big Tariffs (& Barriers)!”

“Nato countries must pay MORE, the United States must pay LESS. Very Unfair!”

Trump has wrongly claimed that the US pays 90% of Nato’s operating costs, the real figure is closer to 22%.

But the US does make up the bulk of all defence spending by alliance members.

EU leaders were left rattled by a recent encounter with Trump at the G7 summit in Canada, where the US president belittled his democratic allies.

They are fearful the next two days could result in similar, and irreparably damage Nato.

Tusk’s comments came at a ceremony marking a new agreement between EU and Nato. The agreement dealing with counter-terrorism, people-smugglers and cybercrime, and traditional defence, has been two years in the making.

Britain had always resisted the EU’s plans for a closer, joint

defence policy, but Brexit has removed that roadblock.