Tune in to "CBS This Morning" on Friday, May 31, for the full interview with Attorney General William Barr.

Attorney General William Barr said he believes special counsel Robert Mueller could have reached a decision on whether President Trump committed obstruction of justice, regardless of long-standing Justice Department policy that prohibits the indictment of a sitting president.

In his first network interview since being sworn in, Barr said the special counsel, who gave a rare public statement Wednesday reiterating some of the key findings in his more than 400-page report, could have concluded the president broke the law without actually charging him — or cleared him of wrongdoing.

"I personally felt he could've reached a decision," he told CBS News chief legal correspondent Jan Crawford during an exclusive interview in Anchorage, Alaska, on Thursday.

"The opinion says you cannot indict a president while he is in office, but he could've reached a decision as to whether it was criminal activity," Barr added. "But he had his reasons for not doing it, which he explained and I am not going to, you know, argue about those reasons."

When he became aware that Mueller would not make a determination in his obstruction of justice probe — which investigated 11 instances in which Mr. Trump tried to derail the Russia investigation — Barr said he and Deputy Attorney General Rod Rosenstein "felt it was necessary" for them to make a decision on the issue.

In a letter to Congress after Mueller submitted his report, Barr said he and Rosenstein concluded that the nearly two-year investigation did not contain sufficient evidence to establish Mr. Trump obstructed justice.

On Wednesday, Mueller said bringing criminal charges against the president was not an option since the special counsel's office was part of the Justice Department and bound by its policies — including a legal opinion barring the indictment of a sitting president.

Mueller also ruled out the possibility of issuing a sealed indictment or making an accusation of criminality without pursuing formal charges. If a sealed indictment became public, it could undermine the president's ability to govern, and making an accusation without bringing charges would not give the president the chance to clear his name in court.

Mueller said the U.S. Constitution "requires a process other than the criminal justice system to formally accuse a sitting president of wrongdoing." Many Democrats said the special counsel's remarks represented a referral of his investigation to Congress, which has the power to impeach and remove a president from office.

Barr said Thursday he did not know what Mueller was "suggesting" in his statement.

"The Department of Justice doesn't use our powers of investigating crimes as an adjunct to Congress," he added.

Asked about accusations that he has been shielding the president from scrutiny since taking office, Barr said he expected the flurry of criticism, which he noted "goes with the territory of being attorney general in a hyper-partisan period of time."

"The Department of Justice is all about the law, and the facts and the substance," he said. "And I'm going to make the decisions based on the law and the facts and I realize that's in tension with the political climate we live in because people are more interested in getting their way politically."