LONDON (AP) — Britain has appointed Karen Pierce as the country’s new ambassador to the United States , replacing a veteran diplomat whose unvarnished portrayal of the Trump administration led to an embarrassing trans-Atlantic spat.

The appointment of Pierce, who is currently ambassador to the United Nations, comes as Britain embarks on critical efforts to strike a trade deal with the United States following its departure from the European Union. It also follows an embarrassing spat over leaked memos that derailed her predecessor.

“It is a time of huge opportunity for the friendship between the U.K. and U.S. and I am delighted that Karen Pierce will take forward this exciting new chapter in our relationship,” Foreign Secretary Dominic Raab said Friday.

Former ambassador Kim Darroch resigned in July. President Donald Trump expressed fury when Darroch's forthright, unfiltered views on the U.S. administration appeared in leaked diplomatic documents that were published in Britain’s Mail on Sunday newspaper.

In the leaked documents, he called the Trump administration's policy toward Iran "incoherent," said the president might be indebted to "dodgy Russians" and raised doubts about whether the White House "will ever look competent."

"We don't really believe this administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept," one missive said.

Trump was outraged, and responded by firing off a series of less than flattering tweets.

“The wacky Ambassador that the U.K. foisted upon the United States is not someone we are thrilled with, a very stupid guy,” Trump wrote in one tweet.

Though former Prime Minister Theresa May backed Darroch, Trump’s public reaction made his job untenable. But it also underscored that the close relationship between the two countries has become increasingly lopsided — a severe problem as the U.K. prepares to set a new path beyond the EU.

Pierce is the first woman to hold the job.