LAST FALL, when he was running for president, Jimmy Carter promised to reduce America's burgeoning defense budget by $5 to $7 billion. Carter's first opportunity to follow through on his campaign pledge came last month, with the submission of his administration's proposed amendments to former President Gerald R. Ford's defense budget for fiscal 1978. But the amendments Carter submitted to Congress last month are a disappointment to those of us who hoped for an aggressive challenge to Pentagon demands for higher spending, and a poor prelude to the Strategic Arms Limitation Talks (SALT) scheduled to resume in Moscow later this month.

Carter's revised defense budget calls for a $2.75 billion reduction in proposed spending, but these cutbacks fall far short of the goals mentioned during last fall's presidential campaign. The Carter amendments will represent only a tiny reduction in the Ford Administration's record-breaking defense budget proposal, permitting a $10 billion increase over the $110 billion budget for the current fiscal year. Moreover, most of this modest reduction is achieved by slowing down procurement of such major weapons systems as the B-1 bomber and the MX ballistic missile, and therefore does not represent a real curtailment in the long-term spending program. In fact, by stretching out the purchasing of these weapons rather than terminating them entirely, the Carter administration may in the long run increase their total cost, once the anticipated effects of inflation are taken into account.

The administration has indicated that postponement of a final decision on the B-1 and MX programs is meant as a signal to the Soviet Union that the U.S. will await results from the upcoming SALT talks before proceeding with major new weapons systems. This approach is reminiscent of the Nixon administration's use of new weapons as "bargaining chips" in arms-control negotiations--a tactic that more often than not spurred Soviet efforts at developing similar weapons rather than mutual reductions at the negotiating table. Moreover, such bargaining chips frequently survive arms control negotiations and grow into full-fledged components of America's defense system: the MIRVed warhead that originally was justified as a bargaining chip now is a familiar element of America's nuclear arsenal. A more effective signal of restraint to the Soviets would be a decision not to proceed at all with the procurement of these new weapons systems, or at least to impose a temporary moratorium on procurement. The latter approach has long been advocated by Paul Warnke, Carter's choice for chief negotiator at the SALT talks.

Unfortunately, even Carter's token reductions are likely to encounter spirited opposition from congressmen whose districts will thereby suffer adverse economic consequences. The decision to end production of the A-7E attack plane, for example, would force the closing of the Vought Corporation's Dallas plant, a move that has angered several influential congressmen, including House Majority Leader Rep. James Wright (D-Tex.) and House Appropriations Committee Chairman George H. Mahon (D-Tex.). Proposals to terminate production of the Minuteman III missile and cutback orders of F-15 fighter planes have provoked similar responses.

WHILE THESE PROPOSALS highlight the difficulty of cutting the military budget when congressional interest in constituent jobs and business investments comes into play, they also exemplify a significant but resolvable paradox in liberal-initiated efforts to reduce defense spending. Pentagon supporters are quick to point out that major cutbacks in weapons procurement are likely to conflict with the goal of higher employment. This ironic justification of defense spending as a public jobs program has often proved to be a formidable obstacle to opponents of Pentagon spending.

The solution, however, is not to preserve existing programs as a form of corporate welfare--and by doing so preserve a structural defect in the American economy--but to judge them on their merits and to deal separately with the adverse economic consequences that might arise in the event of reductions. The justification of Pentagon programs on economic grounds is a sham--it panders to the economic sectors least in need of government aid; those who would lose jobs if the Vought plant in Dallas closed are likely to find jobs more easily than the permanently unemployed of the Dallas ghetto. The central question, as always, is the ordering of governmental priorities, not the preservation of economic interests for their own sake.

While the struggle to reduce an inflated defense establishment will be difficult, it must have a proper beginning. Unfortunately the Carter administration's first step is a halting one. If America's domestic needs and the goal of a safer world are to be met, the next steps must be considerably greater.