The plan to clear the park, which is adjacent to the White House, was devised before Mr. Trump decided he wanted his photo op, the official said, but was not executed until just before he set out. The action, and its timing, drew condemnation from many quarters, including clergy members and political leaders of both parties.
Overnight Sunday, after protesters had defaced the nearby Treasury Department building and a part of the church, St. John’s, had caught fire, top federal law enforcement officials decided that increased security measures were needed around the White House, including expanding the perimeter around the park.
When Mr. Barr found on Monday afternoon that it had not been done yet, he ordered officers on the scene to complete the expansion of the perimeter, but there was not enough time to do it before Mr. Trump made a speech in the Rose Garden, declaring himself a friend to peaceful protest. When Mr. Trump and aides then set out for the church, the protesters in the park were dispersed using gas and other forceful measures.
Mr. Barr was aware that those crowd control measures might be used, but it was supposed to have happened long before Mr. Trump decided that he, Mr. Barr and other officials would walk to the church, the official said.
The Justice Department has confirmed that Mr. Barr is managing the federal law enforcement response to the ongoing protests against police brutality.
Mr. Barr issued a statement on Tuesday saying that “there will be even greater law enforcement resources” deployed in Washington on Tuesday evening.
“The most basic function of government is to provide security for people to live their lives and exercise their rights, and we will meet that responsibility here in the nation’s capital,” Mr. Barr said. He called Monday evening “a more peaceful night in the District of Columbia.”