LONDON -- U.K. Foreign Secretary Boris Johnson refused Tuesday to apologize for the withering one-liners he's made about world leaders in the past but won the support of Britain's closest ally as the country navigates its difficult path out of the European Union.

Johnson, who was hosting U.S. Secretary of State John Kerry in London, said people are "free to rake over" his past comments but that it would "take too long to engage in a full global itinerary of apology" to all those who might have been offended in the past by his "rich thesaurus" of comments, many made in his regular newspaper columns.

Johnson, who was appointed to his new job last week, said he is now focusing on dealing with issues like the unfolding humanitarian crisis in Syria and the troubles in Yemen.

"Those to my mind are far more important than any obiter dicta that you may disinter (from) 30 years of journalism," Johnson said, referring to a term used in law to denote an incidental remark.

The 52-year-old Johnson once described Democratic presidential candidate Hillary Clinton as "a sadistic nurse in a mental hospital." He's also said President Barack Obama's "part-Kenyan" heritage may have given him an "ancestral dislike" of Britain, Kenya's former colonial ruler. He also recently wrote an extremely vulgar limerick about Turkish President Recep Tayyip Erdogan, the leader of a Muslim country.

Kerry for his part, rallied to Johnson's defence, twice remarking on the Latin-spouting British politician's intellect with fulsome praise. The U.S. envoy also underscored his and his nation's commitment to the "special relationship" between Britain and the U.S.

Asked about Obama's remark before Britain's referendum that Britain would be at "the back of the queue" for a trade deal with the U.S. if it left the EU, Kerry said Brexit raised "complicated questions."

"The British have told us they cannot sign any new kind of new trade agreement -- and it stands to common sense that you can't do that -- until they are no longer member of the EU," he said.

But, he added, the U.S. was ready to "engage in conversations" with Britain and "pencil things in" before The U.K. quits the bloc -- a prospect that is more than two years away.

Later the two men were holding talks on Syria with European ministers and discuss the conflict in Yemen with foreign ministers from Saudi Arabia and the United Arab Emirates.