U. S. Helicopters Aid Cambodians

Under an air cover of U. S. helicopter gunships, Cambodian infantrymen fought entrenched North Vietnamese soldiers Wednesday in what may be a decisive battle for Cambodia's lifeline, Highway 4. The highway is Cambodia's major route to the sea.

The fighting raged 60 miles southwest of Phnom Penh at the entrance to Pich Nil Pass, the last stronghold along Highway 4 still held by North Vietnamese forces.

Meanwhile, Secretary of Defense Melvin R. Laird said yesterday that he will recommend use of U. S. airpower in Cambodia, Laos and South Vietnam to reduce American casualties. Laird said he hoped to continue this policy "as long as I am serving in this job."

Laird insisted that this falls within Congressional authorization.