European capitals celebrated a visit by U.S. Secretary of State Antony Blinken in June, as President Joe Biden's top diplomat cracked jokes in French in Paris, posed for selfies with French youth and spoke at length about revitalizing the transatlantic relationship.

It was a breath of fresh air after four years of former President Donald Trump's brash "America First" administration, during which U.S. ties with Europe lurched from one crisis to another amid policy decisions that often blindsided European countries.

But less than three months after Blinken's repair tour, Washington finds itself in an unprecedented diplomatic crisis with France over a trilateral deal with Britain to supply Australia with nuclear-powered submarines that sank a $40 billion contract for French-designed vessels.