Which operation was characterized by measured and limited air actions against military targets in North Vietnam?

Operation Rolling Thunder was the sustained bombing campaign conducted by the United States against North Vietnam from March 1965 to November 1968. This operation was characterized by measured and limited air actions aimed at military targets, with the intent of gradually increasing pressure on the North Vietnamese government and military. The approach was designed to avoid excessive escalation and sought to carefully select bombing targets to avoid civilian casualties whenever possible.

This strategy involved a phased and carefully controlled bombing campaign, which was intended to display U.S. resolve while minimizing the risk of provoking significant retaliation from North Vietnam or escalating the conflict into a broader war. The operation faced various challenges and criticisms, particularly regarding its effectiveness and the restrictions placed on the bombing campaigns.

In contrast, the other operations mentioned had different characteristics and objectives. For instance, Operation Linebacker 2 was known for its more intensive bombing campaign, Operation Farmgate focused on training and support for South Vietnamese forces, and Operation Barrel Roll involved support operations in Laos and was not primarily about limited air actions against North Vietnam.