gas. 18 February: 300 Vietnamese troops assaulted Khmer Rouge positions near Khlong Nam Sai, 19 miles southeast of Aranyaprathet. Fighting began with small arms exchanges and escalated into a Vietnamese barrage with heavy artillery and mortars. Thai troops fired warning shots at Vietnamese soldiers as they crossed the border in pursuit of fleeing Khmer Rouge guerrillas. One Thai villager was killed. 20 February: Vietnamese and Thai soldiers fought on Hill 347, about half a mile inside Thailand's northeastern province of Buriram. A Thai officer was killed and two soldiers were wounded in the fighting, which included an artillery duel across the border. 5 March: Tatum attacked. Green Hill population evacuated to Site B. Dong Ruk, San Ro, Ban Sangae, and Vietnamese Land Refugees are all moved to Site 2. Some 1,000 Vietnamese troops were regularly intruding into Thai territory in attempts to outflank units of the Cambodian resistance groups. 6 March: Thai troops and aircraft forced Vietnamese troops to retreat from one of three hills on Thai territory which the Vietnamese had captured during preceding days. Royal Thai Air Force fighter-bombers flew missions against about 1,000 Vietnamese who crossed the Thai-Cambodian border in two places. Some 60 Vietnamese troops were killed in the Thai counterattack. 7 March: Thai army troops supported by artillery and A-37 Dragonfly aircraft recaptured three hills seized by intruding Vietnamese soldiers. Hundreds of Vietnamese were said to have been driven back across the border into Cambodia. However, the Vietnamese counterattacked against Hill 361 on Thai soil behind the besieged Cambodian guerrilla base at Tatum, and the results of the battle were not immediately clear. 14 Thai soldiers and 15 Thai civilians had been killed. 4 April: A clash occurred at Laem Nong Ian, after five Vietnamese intruded about 875 yards into Thailand. 6 April: Thai Border policemen killed a Vietnamese soldier in Thailand during a 10-minute fight near the border. 20 April: At southeastern Thailand's Trat Province, some 1,200 Vietnamese troops attacked Thai positions situated 3 to 4 km from the Gulf of Thailand. Instead of withdrawing the Vietnamese set up a permanent base on a hill in Thailand, about a half-mile from the border, where they laid mines and built bunkers. Later, escalating Thai attacks had pushed some of the Vietnamese back into Cambodia, but the Vietnamese dispatched a fresh battalion of 600 to 800 men to reinforce the hilltop. 10 May: A Thai soldier