Secretary of State Rex Tillerson said the U.S. takes "full responsibility" for the leak of British intelligence from its investigation into the Manchester bombing.

"We take full responsibility for that and we are, we obviously regret that that happened," Tillerson said during a visit with London Mayor Boris Johnson. Tillerson made the trip Friday as an expression of U.S. solidarity with the U.K. following the attack at a Manchester concert, which left 22 dead and dozens of others injured.

Photos which appeared to show the bombing materials used in the bombing were shared with U.S. intellegence and then were published in the New York Times earlier this week, angering top British officials, including Prime Minister Theresa May. She talked with President Trump about the leak on Thursday and made it clear to him that "intelligence shared must remained secure." The U.K. stopped sharing intelligence with the U.S. briefly, but resumed sharing after "receiving fresh assurances," a top British counterterrorism official said.

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After his meeting with May, the president called the leaks "deeply troubling" and said they "pose a grave threat to our national security." And he also ordered the Justice Department to investigate the matter and prosecute the culprit, "if appropriate."

Tillerson reiterated the U.S. condemnation of the leak, and said that the "special relationship" between the U.S. and the U.K. "will certainly withstand this particular unfortunate event."

During his London trip, Tillerson and Johnson also discussed Syria, Iran, North Korea and the importance of intelligence sharing across the world. He and Johnson also wrote condolence messages in response to the Manchester attack.