U.S. Uses 7 1/2 Ton Blockbusters On Troops Besieging Fire Base 6

U.S. planes are dropping seven-and-a-half ton blockbusters on the North Vietnamese besieging Fire Base Six, in the first use of this powerful bomb on troops. U.S. military sources said Monday.

The bomb had previously been used for blasting out heavy jungle growth and clearing landing spaces for helicopters. "We are not as interested in putting in helicopter pads as we are in knocking out troop concentration." a military source said about the latest use of the blockbusters.

Fire Base Six, a military outpost close to the juncture of Laos. Cambodia and South Vietnam has been under siege since March 31.

296,500 To Go

In Saigon, the U.S. Command announced American troops in Indochina now number 296,500, equal to the troop level four-and-a-half years ago. The peak level was 513,000 troops in April 1969. The total is due to drop to 284,000 by May 1.

President Nixon said last week that 100,000 troops will be withdrawn between May 1 and Dec. 1 as part of the Vietnamization plan. As withdrawals continue, the remaining U.S. troops around Saigon will be turned into a hard-hitting strike force, a field commander said.