US President Donald Trump on Saturday appeared to be partially walking back remarks on the role of non-US Nato troops in Afghanistan amid growing outrage from European allies.

But Trump's claim in a Fox News interview that Nato sent "some troops" but "stayed a little back, a little off the front lines" brought fresh condemnation on Saturday.

He offered an olive branch to Britain after an angry response to his comments earlier in the week, praising British soldiers.

"The GREAT and very BRAVE soldiers of the United Kingdom will always be with the United States of America!" Trump said on his Truth Social platform.

"In Afghanistan, 457 died, many were badly injured, and they were among the greatest of all warriors. It's a bond too strong to ever be broken."

But Britain was not the only Nato ally to express anger at Trump's earlier remarks, as other European leaders reacted sharply on Saturday, recalling the sacrifices their soldiers had made.

Trump's comments follow a bruising transatlantic crisis over his threats to seize Greenland – an autonomous Danish territory – now seemingly defused.

The US president on Wednesday backed away from threatened tariffs on Europe for opposing his claims on the Arctic island. (AFP)