Communist F orces Land StaggeringBlows To SaisronLBy liKKT OKUL1CY SAIGON CUP1) - Tank led 1 Communist forces captured ‘ another provincial capital 1 today, shut dawn Bien Uou air- base for nearly six hours with ' an artillery barrage and muted ’ a South Vietnamese regimentalbase outside the province- capital of Xuan Loc.- The series of military sct-- backs shook the morale of war-- weary government troops fight-I ing to keep the remnants of a t dwindling South Vietnam from ' falling into Communist hands.They coincided with reports (lie- Communists had established an i air base at Pleiku in the Central Highlands.5 The Communists, moving under a barrage' of more thanI 1,000 shells, overran the 2,000-6 man regiment of Ihc. lath 5 Division at Gia Kiem, eiglit s miles northwest of Xuan Loc,II which is Ml miles northeast of Saigon. By nightfall, field5 reporters said, the batteredt outfit had retreated to Trang Bom, only 23 miles from the- capital.i, Thu regiment, which some y field reports said appeared to it be 80 per cent destroyed, blew e up eight American-suppliedn 105mm and 155mm howitzere artillery pieces before fleeing, military sources said.Sources said other govern-11 ment troops today abandonedn the province capital of Phan Y Hang, on the south China Sea y coast IC5 miles northeast of'J Saigon, when it was atlaekedu by a 5,000-niiin Communistforce moving w i th ta nk supjjort. u U was the inMi provincial it eapital lost to the Communistsis in the current offensive and leftst the North Vietnamese and VielCong in full control of Ninh rf Thuan Province. The Commu-in nists now control 18 of Southa, Vietnam’s 44 provinces andtwo-thirds of the nation's territory.Military sources sard government warplanes bombed thePhan Rang air base after thecity's 2,500 defenders fled to ships wailing offshore. Two South Vietnamese generals were feared trapped in the city, and Commmunisl tanks were reported cruising the streets.Intelligence sources said the North Vietnamese and Viel Cong had established what they considered their main air base in the fallen Central Highlands province capital of Pleiku, 230 miles north of Saigon.The sources said at least one Korean War-vintage MIGlQ jet and some Soviet-built helicopters were on the ground at the Pleiku airfield.Communist troops meanwhile today fired more man 30 rounds of 130mm artillery into the government's major airbasc at Bien Hoa, 14 miles northeast of Saigon and headquarters for South Vietnam’s Military Region m.Military sources said the barrage destroyed at least four F5 jet fighter-bombers on the ground and the base was closed for nearly six hours. The sources said at least two airmen were killed and three injured in IIic 7 a.m. shelling. The 130mm gun is Ihe biggest and most feared weapon in the Communist arsenal ,with a range of 17 miles.Despite the defeat sustained by the 18th Division outside Xuan Loc, the strategic * city apparently remained in government bands. The South Vietnamese units ul Gia Kiem moved down provincial Highway 20 and then onto HighwayPHNOM PENH (UP!) — Black-shirted guerrillas battled their way into Phnom Penh today, driving back diehard1 on which they made their way to Trang Bom, field reports said.Although Bien Hoa was closed during the morning, government F5 jets were flying missions around Xuan Loc by early afternoon.Two busloads of American contractors were turned back at the gales of the shell-ballered air base after the shelling and ordered to return to Saigon.Military sources said Communist infantry, attacking under the cover of a 1,000-round shelling barrage, overran a government outpost eight miles northwest of Xuan Loc*.'Die sources said Ihe defenders destroyed eight American-made howitzers before retreating toward Xuan Loc, 33 mites northeast of Saigon along French-built Highway 1.•The military command in Saigon also reported fierce ground fighting less than Cwd miles northwest of Xuan Loc. A. spokesmans aid 32 Communists were killed in one clash. Three government soldiers were reported wounded.The pilots of government warplanes reported killing 121 Communists and destroying 18 artillery pieces Tuesday In raids nine miles northwest of Xuan lx)C.In Washington, Secretary of State Henry Kissinger said Tuesday the United Slates would reduce1 the number of Americans in South Vietnam to a minimum level,'1bridge burned down, trapping thousands of terrified civilians hiding from the bombs andbullets.Guerrillas Are In Phnom Penh