The United States has quickly deployed to the Persian Gulf the most technologically advanced combat force ever assembled outside the NATO arena. But high-tech gadgets are only as good as the low-tech nuts and bolts that back them up. Government documents and defense sources have raised serious questions about the long-term staying power of the U.S. forces, because the Pentagon has neglected the basics in favor of bells and whistles.

Nearly a decade ago, a maverick Pentagon budget analyst warned that the Defense Department had "a tendency to reduce our current readiness to fight in order to modernize for the future." U.S. combat readiness has increased since then, but the analyst's predictions are still true. The spending spree of the Reagan years put too much emphasis on buying space-age gadgetry instead of sticking to the basics of logistics and support.

During the Reagan presidency, the Pentagon brass was all smiles. Their budgets ballooned, and every program benefited. But instead of spending the money evenly across the board, the Defense Department allocated the lion's share to sexy programs that broke the bank.

The White House wasn't all to blame. Congress liked the big-ticket items too. "It's much easier for a congressman or president to say he is strengthening our defense by buying 40 new jets than buying 4,000 widgets," naval analyst Norman Polmar said.

Money spent on basic readiness did steadily increase just by virtue of the Reagan largesse toward the Pentagon, but support programs lost their appeal relative to research and development. The basics didn't get the attention they deserve. And when budget cuts had to be made in the Reagan years, nuts and bolts were the first to suffer.

The case of the Army's $13 million attack helicopter, the Apache, shows what can happen when spare parts are an afterthought. A recent congressional investigation found that the Apache was "fully mission capable" less than half of the time that it was called on in 1989. Why? "Logistical supportability has not enjoyed a high enough priority," the congressional investigators said. In other words, the Army blew the wad to build the Apache and didn't have enough left over to keep it in the air.

The problems for the Apache are likely to be magnified in combat, according to the investigators. And the high-tech design of the helicopter also promises to cause problems. When the Apache was tested in the desert last year, the Army later admitted that "within three days ... 50 percent of the {Apache} mission had to be aborted due to sand ingestion."

The humidity in Panama also wreaked havoc for the temperamental Apache. Nevertheless, it is one of the Army's primary weapons against Iraq's nearly 5,500 tanks.

A second congressional investigation paints a similar picture of the Air Force readiness. The investigators looked at C-5 and C-141 cargo planes that are hauling people and supplies to Saudi Arabia.

Over the years, the Air Force has been short on spare parts for those planes, effectively grounding many of them during peacetime. To keep operations going, the Air Force dipped into its wartime reserves of spare parts. From 1984 to 1988, figures show that on the average the Air Force plundered war-reserve spare parts for more than half of the repair jobs on broken down C-5s and C-141s. Many of those stocks have yet to be replenished.

The plundering has produced major shortages in wartime reserves which, according to the investigators, "will seriously reduce the hours of operation and the tonnage that can be moved" in the first 30 days of a war. In 1989, the investigators said, war reserve spare-part kits for the cargo planes were down 27 percent. By Air Force criteria, a shortfall of 36 percent or more would cancel a wartime mission.

The plundering of war reserves may not be limited to just the C-5 and C-141. "It's my impression this kind of stuff goes on across the board in the Air Force," one Defense Department source told our associate Dean Boyd.

The picture is equally grim in the Navy. Retired Rear Adm. Edward J. Walker, former chief of the Navy Supply Corps, has predicted that by 1991, the Navy's spare parts and supply budgets will have dropped 26 percent and 20 percent respectively from 1987 levels. The result, he says, is that the number of Navy planes that are fully ready for a mission will drop by 5 percent and the number of ships by 4 percent.

Those trends add up to danger for U.S. soldiers facing what could easily be a long-term conflict. One national security analyst told us that "today's operation in the Mideast has the potential to strain DOD's logistics support as much as Vietnam."

With the inclination of most top brass to overrate the capability of their troops during the buildup, Defense Secretary Richard Cheney would be well advised to ask for proof when he is briefed on the extent of logistical support in the Persian Gulf.