(CNN) U.S. Secretary of State John Kerry kept his composure -- just -- as he endured an awkward joint press conference with his new British counterpart, Boris Johnson.

The pair faced journalists at the Foreign Office in London Tuesday in Johnson's first news conference since his controversial appointment by the UK's new Prime Minister, Theresa May.

The two met to discuss the world's most pressing issues and to reaffirm the two country's oft-vaunted "special relationship" in the face of the UK's decision to leave the EU, but the tone from the assembled reporters was combative.

Johnson was taken to task by the AP's Brad Klapper for what he cast as insulting references to world leaders and other notable figures, including accusing U.S. President Barack Obama of having a "ancestral dislike for the British Empire" and describing presumptive Democratic Presidential nominee Hillary Clinton as a "sadistic nurse in a mental hospital."

Klapper asked the new Foreign Secretary: "Do you take these comments back? Or do you want to take them with you into your new job as some sort of indicator of the type of diplomacy you will practice?"

Kerry could barely smother a smile and busied himself with his notes as the question continued.

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Johnson, who was a chief architect of the UK's "leave" campaign in June's EU referendum, gave a typically verbose stuttering response.

"I'm afraid there is such a rich thesaurus now of things that I have said that have been -- one way or another, through what alchemy I do not know -- somehow misconstrued, that it would really take me too long to engage in a full, global itinerary of apology to all concerned."

He added that those he has met "in the proper context" understand him.

Dismissive

He dismissed the criticisms, suggesting that the challenges facing the U.S. and UK, including an unfolding humanitarian crisis in Syria, should take precedence. He also referred -- twice -- to a deteriorating situation in "Egypt." It is widely understood that he misspoke and was indeed referring to the attempted coup in Turkey -- a country whose leader he recently insulted in a crude limerick.

In what became a recurring theme focusing on his record, Johnson was also asked why his U.S. counterpart and others should trust him, given his "unusually long history of wild exaggerations and frankly outright lies."

Kerry again heroically masked his expression, which was beginning to look aghast.

Johnson demurred, again suggesting that the press conference focus on the "very heavy agenda we have before us today."

John Kerry's face when a US journalist accuses Boris of making "outright lies" is quite something. pic.twitter.com/s8zR55BE1r — Richard James (@richjamesuk) July 19, 2016

Ever the consummate diplomat -- beyond a few grimaces and a well-covered smirk -- Kerry refused to be drawn on the changing face of British politics or his British counterpart's record.

"I think that it is clear that no shift in administrations, and I'm speaking for us either, in either of our countries is going to alter or undermine the bonds that we have," he said.

He added that the "special, unbreakable" ties between the two countries were reaffirmed and that it was a "genuine expression of a feeling of friendship."