Early April: PVNA destroyed the camp of Phnom Chat, civilians evacuated to Red Hill. Sihanouk's Camp David was attacked and civilians moved to Green Hill. One Thai jet was shot down. 1 April: The Thai Government reported that a large force of Vietnamese troops had attacked a total of 3 refugee camps along the Thai-Cambodian border. The New York Times reported that at least 7,000 civilians had fled westward into Thai territory. 3 April: At least 100 Vietnamese troops crossed into Thailand and fought hand-to-hand with a Thai border patrol, killing five Thai soldiers and wounding eight. An assault on Ampil Camp, the KPNLF headquarters, failed because KPNLF sabotage units had blown up several fuel depots in the weeks prior to the attack, leaving the division short of diesel and unable to mobilise its armour. 27 December: Vietnam moved troops, tanks and armoured personnel carriers into an area near the eastern border of Thailand and was apparently preparing to attack Cambodian guerrillas. About 350 Vietnamese troops with several T-54 tanks and armoured personnel carriers arrived in Thmar Puok village in western Cambodia, 14 miles southeast of the major base of the non-Communist Cambodian rebels and 16 miles from the Thai frontier. Thai military and security officials expected Vietnamese forces to begin a dry-season offensive against Cambodian guerrillas next month. December: Vietnamese troops clashed with Thai troops repeatedly on land while Vietnam People's Navy gunboats opened fire on a fleet of ten Thai fishing trawlers about 20 miles off the southern Vietnamese coast, seizing five trawlers and capturing 130 fishermen. 1984 25 March-early April: Hanoi launched a 12-day cross-border operation into Thai territory in pursuit Khmer Rouge rebels, using Soviet-made T-54 tank, 130-mm artillery, and some 400–600 troops. As a result, Thai artillery and air power had to be called into action, resulting in dozens of casualties on both sides and the downing of another Thai military aeroplane. Vietnam's cross-border raid, along with Thai military and civilian casualties, was reviewed as seriously undermining Thailand's security. Minor clashes occurred in the area of the Khmer Rouge camp, the Chong Phra Palai Pass linking Cambodia and Thailand. 15 April: Six hundred Vietnamese troops of the 5th Division and the 8th Border Defense Regiment first shelled, then entered Ampil Camp, a guerrilla base on the border, killing 85 and wounding about 60 Cambodian civilians. The dawn attack was supported by tanks and artillery. About