Trail Is TargetOfNew OperationLANG VEI, South Vietnam Thedrive up what used to be French colonial Highway 9 to this Laotian border outpostis a tiresome 30 miles of smoke and dust and bouncing over the ruts of tank tracks between lush and deadly hills. , .lt;The ruins of a decade of war, especially the massive siege at nearby Khe Sanh three years ago, are everywhere, and so are the sounds and smells and sights of the ‘military machine that punched back Into this areaslx days ago.-;Blasted-bulJ dings'andblownridges, ghostly tree stumps, huge shell craters, and the rusting remains of abandoned war machines are everywhere. RESHAPING COUNTRYSIDE As (die, road climbs Into thp •om-Oon*, «a .nBar-Ahe ft' Blgfnray 1, the Vegetation gets thicker and so does•i -Iospital.the dust. Gradually a thin ochre veneer covers'the tree leavesand the fine red laterite particles tossed Into the air by the trends and wheels of vehicles sift into your nostrils and your mouth.The sound of artllleryechoes through the canyon walls, and there Is a constant clatter not only of tanks and trucks but of helicopters and gunshlps flying cover overhead.A dirt track cuts-off into the wilderness In the -wake of an Infantry battalion that Is slog-glnglts way across cotmTry to Khe Sanh, building a pioneer road to shorten the trip and get tanks off Highway 9*s fragile surface.. At Khe Sanh more clouds of dust are rising from construe- Idik'a brand new, airsick*--] m repair of an old oUTST ^ ndoned by the Marines in theNspring of 1968 after the siege 1 had ended.BUILDING ... FOR WHAT?Troopers there say they've been told they'll be there at least three months, and two battalions of Vietnamese have Just been lifted in to reinforce the three American Battalions sweeping the countryside around the base.More are expected.Here at Lang Vel, five miles West, tanks and bulldozers are chewing a huge clearing out of the rain forest just over a mHe from the Laotian border .It isa major new outpost for\the 1st Brigade of the 5tb Mechanized Infantry Division, which is running this operation. - . ■No one here will say exactly why,No one her£ will say either how Americans •, expectto protect aii ImporTahfposl so close to the border unless there are friendly troops on the other side.