Reagan faces an uphill battle on defense buildup

President Reagan has been using his August vacation to once again beat the drum for a United States military buildup, while criticizing members of what he terms the ''so-called peace movement'' as misguided Neville Chamberlain types.

With recent congressional approval (at least tentative) for the MX missile and other weapons, it would seem that the Pentagon is largely getting its way. But latest developments indicate that the administration will continue to fight an an uphill battle for its defense policies.

House and Senate conferees recently halved to 5 percent the rate of increase for military spending the administration sought in 1984. Criticism of Pentagon management is growing, led by Republicans who insist on a more tightly run ship. There is rising concern among uniformed experts and some key civilian leaders that the administration's military plans are too ambitious given available resources, and that, for example, some important parts of US defenses will be slighted by insistence on a 600-ship Navy.

Speaking to an American Legion gathering in Seattle this week, the President said his policies have produced ''new hope for arms reductions and a more secure world.''

But as US military exercises continue in Egypt and Central America and shortly will begin in Europe, domestic polls show continued doubts (especially among women) about Mr. Reagan's seriousness as an avowed peace-seeker. In Germany, where American-built Pershing II nuclear missiles (which have failed three of four recent test flights) are to be based in just four months, a large majority of German citizens are opposed to this new NATO deployment.

The political nature of such issues is highlighted by the announced retirement of Sen. John Tower (R) of Texas, chairman of the Armed Services Committee. This means Senator Tower, a leading Pentagon champion on Capitol Hill , will be a lame duck for the next 16 months. And with Senate majority leader Howard H. Baker Jr. (R) of Tennessee retiring as well, it gives Democrats increased hope of regaining Senate control next year and putting what would likely be a somewhat more liberal stamp on US defense policies.

All of this will make it more difficult for the Reagan administration to sustain its momentum on military issues in coming months, as the peace issue increasingly dominates the 1983-84 political season.

In order not to be left behind by the growing congressional rumblings for Pentagon reform, Senator Tower has begun hearings on defense management in the Armed Services Committee he chairs. But the efforts in this relatively friendly forum may already be irrelevant. Other Republicans want more than just talk.

Conservatives like Sen. Charles Grassley (R) of Iowa are as outraged as more traditional Pentagon critics by reports of spiraling spare parts costs. The Senate Government Affairs Committee chairman, William Roth (R) of Delaware, is one of those pushing for an independent office to test new weapons.

Sen. Mark Andrews (R) of North Dakota wants manufacturers warranties as well.

''Taxpayers have been milked out of billions of dollars on shoddy equipment that not only cost a fortune to buy, but then cost a fortune to fix because it didn't work right when we got it,'' says Senator Andrews.

There have been some improvements in defense management. Defense Secretary Caspar W. Weinberger and other administration officials correctly point out that the spare parts scandal was revealed through internal audit. While it disputes some Pentagon figures, the Congressional Budget Office notes that the most recent quarterly report on weapons cost overruns ''is the smallest cost increase reported for a fourth quarter since 1973.''

Nevertheless, congressional conferees cut the administration's defense authorization request by $10.5 billion, and full House and Senate are expected to follow suit when lawmakers return to Washington after Labor Day.

Conferees also put limits on the testing of anti-satellite weapons and forbid production of a new nuclear artillery shell. From Europe, there was a bit of bad news for administration defense planners as well. A new public opinion poll showed that only about 20 percent of West Germans favor deployment of the Pershing II missile there.

In his Seattle speech this week, President Reagan pronounced himself encouraged by what he acknowledges is ''modest'' movement in arms control negotiations with the Soviet Union. Progress here, he said, is due to his administration's strong defense and arms control positions.

On both sides of the Atlantic, however, strong doubts remain. And without clearer signs of progress at the arms talks in Geneva, these are likely to increase as key political dates approach.