Marco Rubio warns European leaders mass migration is 'a crisis destabilising the West'

Mr Rubio stressed the importance of maintaining control of national borders, claiming it was not an expression of xenophobia or hate.

He dubbed the ability to protect borders: "A fundamental act of national sovereignty."

He told the conference: "Mass migration is not, was not, some fringe concern of little consequence. It was and continues to be a crisis which is transforming and destabilising societies all across the west."

Mr Rubio, while praising Europe's history, delivered more subtle criticisms, at times implying that European leaders had turned their backs on worthwhile elements of the continent's past.

He said: "We in America have no interest in being polite and orderly caretakers of the west’s managed decline. We do not seek to separate, but to revitalise an old friendship and renew the greatest civilisation in human history.

"What we want is a reinvigorated alliance that recognises that what has ailed our societies is not just a set of bad policies, but a malaise of hopelessness and complacency.

He continued: "We want allies who are proud of their culture and of their heritage, who understand that we are heirs to the same great and noble civilization, and who together with us, are willing and able to defend it and this is why we do not want allies to rationalize the broken status quo."

Mr Rubio also argued it had been President Trump, rather than the UN, that was solving crises in Gaza and Ukraine, as he called on Europe to follow the lead of the US.

He said: "In a perfect world, all of these problems and more would be solved by diplomats and strongly worded resolutions. But we do not live in a perfect world.

"We cannot continue to allow those who blatantly and openly threaten our citizens and endanger our global stability to shield themselves behind abstractions of international law which they themselves routinely violate.

"This is the path that President Trump and the United States has embarked upon. It is the path we ask you here in Europe to join us on."

The reaction from European politicians present was positive, with diplomats saying they had been "reassured" by Mr Rubio's comments.

EU Commission Chief Ursula von der Leyen said: "[Mr Rubio] is a good friend, a strong ally...and this was, for me, very reassuring to listen to him.

"We know that in the administration, some have a harsher tone on these topics. But the Secretary of State was very clear. He said 'We want strong Europe in the Alliance', and this is what we are working for intensively in the European Union."

German Foreign Minister Johann Wadephul added: "We know that he is a true partner...I would say [it was] a very clear message from Secretary Rubio that we have...to stay and stick to our international rules-based order, which is, of course, in first line the United Nations."