Campaign Z was notable for escalations of the Laotian Civil War conflict. The Vietnamese Communists brought 130 mm field guns and T-34 tanks into action in Laos for the first time. The Vietnamese People's Air Force also launched MiG 21 attacks into Lao air space to challenge the Royalist side's air supremacy. On its side, the Royal Lao Government and its Central Intelligence Agency backers imported copious numbers of mercenaries from the Kingdom of Thailand as reinforcements, and depended on American air power support, including Arc Light strikes by B-52 Stratofortresses. The Kingdom would narrowly survive Campaign Z.