Less than a week after Iraq invaded Kuwait on August 2, 1990, VMA-542 was ordered to deploy to the Persian Gulf in support of Operation Desert Shield. With the squadron of twenty AV-8Bs, Tomassetti flew from North Carolina to southern Bahrain and arrived at Sheik Isa Air Base on August 21. He spent the next two months preparing for combat by flying training missions and "standing alerts" in which pilots took turns sitting in or near their armed aircraft, ready to scramble on short notice in the event of hostilities. The squadron moved closer to the expected area of conflict on November 4–5, repositioning to the King Abdul Aziz Naval Base and airfield complex in Saudi Arabia near the Kuwaiti border. Tomassetti and the squadron continued to fly training sorties with a focus on close air support missions intended to protect ground troops that would soon engage enemy forces.