U.S. JETS BOMBING CAMBODIAN TRAILS ON DEEPER RAID
US fighter-bombers and gunships, restricted to flying maximum of 21.7 mi into Cambodia to support ground operations, found to have been ranging much deeper into NE Cambodia since allied Incursion en Apr 30; attacks geared to destroying new enemy infiltration routes; Amer officials, Saigon, unclear on whether raids, never before discussed publicly, will cease on June 30; Adm has made it clear that US would not provide air combat support for S Vietnamese forces beyond established limit but has never excluded possibility that Amer planes would bomb enemy supply lines and bases beyond that limit; such air activities would be permissible under Cooper-Church amendment; N Vietnamese ingenious techniques to move certain necessities by water and US countermoves to block them described