Egypt's Ras Banas military base is a critical part of the Pentagon's master plan for bringing military power to bear hurriedly in the Middle East and Persian Gulf.

The plan has been to spend between $500 million and $600 million to lengthen the runways at Ras Banas, a finger of land on the Red Sea pointing toward the heart of Saudi Arabia, and to build storage facilities for war gear and platforms for troop tents.

Under Pentagon war plans, a quick-response division such as the 82nd Airborne would fly from the United States to Ras Banas, rest and take on water, store fuel and backup weaponry and then race to the trouble spot.

The plan is to pour cement platforms on the desert floor to hold troop tents, tanks and trucks in an emergency. A small caretaker force of Egyptians and Americans would stay at the base in periods of calm in the Middle East and Persian Gulf.

"Ras Banas is one of the two most vital places in the region," said Robert W. Komer, Pentagon policy director during the Carter administration who helped negotiate U.S. military rights to the austere Egyptian base and plan its expansion.

The other vital spot, he said yesterday, is the British-owned island of Diego Garcia in the Indian Ocean, with Oman's Masira also a crucial launching pad for U.S. military forces.

Komer said the Carter administration plan called for longer and wider runways at Ras Banas to accommodate B52 bombers rather than use more distant Diego Garcia for them. "This may still be the plan," he said.