was killed after stepping on a land mine while on patrol. 11 May: Thai jet fighters and heavy artillery pounded Vietnamese troops occupying a hill half a mile inside Thailand, and Thai soldiers poised for an assault on the heavily mined position. The Thais bombed and shelled the Vietnamese before an infantry operation was to be launched in the Banthad Mountain range, 170 miles southeast of Bangkok. The Vietnamese were dug in along the hill and had laid a string of mines to counter any Thai ground assaults. Seven Thai soldiers were killed and at least 16 injured. Radio Hanoi reported a Vietnamese Foreign Ministry statement denying the latest reported incursion into Thailand. Thailand accused Vietnam of at least 40 cross-border forays in search of Cambodian guerrillas since November 1984, but the Vietnamese government had denied the charges. 15 May: Vietnamese and Thai soldiers clashed for about eight hours with mortars, antitank cannons and machine guns. 17 May: Thai soldiers drove intruding Vietnamese soldiers back into Cambodia in intense fighting along Thailand's southeastern border. After more than a week of fighting, Thai rangers and marines seized part of a Vietnamese-occupied hill just inside the Thai border the previous days. May: An approximate 230,000 Khmer civilians were in temporary evacuations in Thailand after a very successful Vietnamese dry season offensive. 26 May: Vietnamese soldiers crossed into the Thai province of Ubon Ratchathani from northern Cambodia, apparently searching for Cambodian guerrillas. A Vietnamese force killed five Thai soldiers and a civilian in a one-hour clash with Thai border patrols in northeast Thailand. The fighting prompted Thai provincial authorities to evacuate about 600 civilians from two border villages to safer areas in the Nam Yuen district. 13 June: Thai forces battled 400 Vietnamese troops who crossed into Thailand. 1986 23 January: A Vietnamese barrage was aimed at a Thai marine outpost in Haad Lek, a village at the southern tip of the border. The Vietnamese fire came from a hill overlooking Haad Lek, inside Cambodian territory. "This appears to be a deliberate provocation by the Vietnamese", a Thai Navy spokesman said. "It does not look like a spillover of fighting inside Cambodia." A Thai warship in the Gulf of Thailand responded by shelling the Vietnamese artillery base. The warship fired more than 100 shells and the Vietnamese more than 70 shells. 25 January: Vietnamese heavy guns pounded a Thai border post, killing three