Congress’ government watchdog office and the Pentagon’s F-35 Joint Program Office (JPO) are at odds over how to structure the jet’s Block 4 modernization effort.In a March 23 hearing, Government Accountability Office (GAO) Director of Acquisition and Sourcing Management Michael Sullivan argued that the Block 4 estimated cost justifies its management as a separate program, But F-35 Program Executive Officer (PEO) Air Force Lt. Gen. Christopher Bogdan countered that breaking it off would create an administrative burden and add to…