"The Inspector General’s report now makes clear that the FBI launched an intrusive investigation of a U.S. presidential campaign on the thinnest of suspicions."

 https://www.politifact.com/factchecks/2019/dec/11/william-barr/barr-disputes-inspector-generals-report/

 Our ruling

Barr said, "The Inspector General’s report now makes clear that the FBI launched an intrusive investigation of a U.S. presidential campaign on the thinnest of suspicions."

The report found that the decision to start the Russia investigation was justified. But the FBI did secure a FISA warrant to surveil Page, a technique that is permitted but considered intrusive.

We rate Barr’s statement Mostly False.