Kevin McAleenan, the acting Homeland Security secretary, said in an interview that aired Sunday that the practice of separating migrant families the southern border with Mexico was “effective” but said it was not successful in the long run because it lost the public's trust.

McAleenan is a longtime border officer and is well-respected by members of Congress and within the administration. He was named the acting secretary earlier this month after Kirstjen Nielsen resigned.

"The enforcement of the law against parents who violated our border laws and brought children with them was effective," he told "60 Minutes." He said, "but it didn't work in the sense that we lost the public trust in the implementation of that initiative. And I agreed with the president's decision to stop it."

The Justice Department said in a court filing earlier this month that it will take at least a year to review about 47,000 cases of unaccompanied children taken into government custody between July 1, 2017 and June 25, 2018 — the day before U.S. District Judge Dana Sabraw halted the general practice of splitting families.

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The federal government has six months to identify potentially thousands of children who were separated from their families, a judge ordered last week. The American Civil Liberties Union, which sued over family separations, wanted the job done in three months, which White said was unrealistic. The ACLU agreed Thursday to six months.

McAleenan said "when you lose the public trust in a law enforcement initiative, that means it wasn’t successful."

The Associated Press contributed to this report