U.S. Secretary of State Marco Rubio on Saturday offered a reassuring message to European allies, saying Washington wanted to recharge the transatlantic alliance so Europe could help the U.S.’ mission of global “renewal”, after more than a year of President Donald Trump’s often-hostile rhetoric toward traditional allies.

Speaking at a security conference in Munich after months of turmoil in U.S.-European relations sparked by Trump's vows to seize Greenland and his often derisive remarks about U.S. allies, Washington's top diplomat struck a markedly soothing tone.

"We do not seek to separate, but to revitalize an old friendship and renew the greatest civilization in human history," Rubio said, calling for "a reinvigorated alliance."

"We want Europe to be strong," Rubio said, adding that the continent and the U.S. "belong together."

He echoed Trump administration's oft-stated assertion that immigration posed a threat, saying that "mass migration" was "a crisis which is transforming and destabilizing societies all across the West."