US Secretary of State Marco Rubio has assured European leaders the US does not plan to abandon the transatlantic alliance, saying its destiny will always be intertwined with the continent's.

He told the Munich Security Conference: We do not seek to separate, but to revitalize an old friendship and renew the greatest civilization in human history.

Rubio criticized European immigration, trade, and climate policies, but the overall tenor of the closely-watched speech was markedly different from Vice-President JD Vance's at the same event last year, during which he scolded continental leaders.

European Commission President Ursula von der Leyen said she was very much reassured by Rubio's remarks.

Rubio, the Trump administration's most senior diplomat, said it was neither our goal nor our wish to end the transatlantic partnership, adding: For us Americans, our home may be in the Western Hemisphere, but we will always be a child of Europe.

And I am here today to leave it clear that America is charting the path for a new century of prosperity, and that once again we want to do it together with you, our cherished allies and our oldest friends.

However, he repeated several criticisms repeatedly levelled at Europe by the Trump administration, including describing immigration policies as a threat to civilization, and saying a climate cult had taken over economic policy.

On trade, he said Europe and the US had made mistakes together by adopting a dogmatic vision of free and unfettered trade.

He reiterated calls from the US for Europe to invest more in defense, stating: We want allies who can defend themselves so that no adversary will ever be tempted to test our collective strength.

In response, Von der Leyen said: [Rubio is] a good friend, a strong ally. And this was, for me, very reassuring to listen to him.

Elsewhere in his half-hour address, Rubio stated that the system of international cooperation must be rebuilt and singled out the UN for criticism, saying it had played virtually no role in resolving conflicts in Gaza and Ukraine.

He also expressed concerns about the nuclear programme of Iran, asserting that the US would continue to press for agreements to curb Iran's nuclear capabilities amidst rising tensions.

Speaking later at the conference, Ukraine's President Volodymyr Zelensky dismissed the possibility of respite from Russia, asserting that no one in Ukraine believes that Putin would cease hostilities, branding him a slave to war.