What was recognized as the first major American offensive in Vietnam?

The first major American offensive in Vietnam is recognized as Operation Starlight, which took place in August 1965. This operation marked a significant shift in U.S. military involvement in the region, transitioning from primarily advisory roles to direct combat operations against Viet Cong forces. The aim of Operation Starlight was to seek and destroy Viet Cong forces in the Quang Ngai Province, utilizing a coordinated tactic involving Marine aircraft and ground troops.

This operation is notable for its scale and the context of the Vietnam War, as it demonstrated the U.S. commitment to engage in more aggressive operations to counteract the growing influence and military actions of the Viet Cong. Other options, such as Operation Rolling Thunder, were more focused on sustained aerial bombardment rather than ground operations, and operations like Neptune Spear and Enduring Freedom are related to conflicts in different regions and times, specifically Iraq and Afghanistan, rather than Vietnam.