The irony is unmistakable. Here are presidential contenders Ronald Reagan and Walter Mondale telling voters how eagerly they will maintain the military strength of the United States - although in different ways. Mr. Reagan stresses weapons systems and firmness. Mr. Mondale stresses arms control and conventional weapons over nuclear systems.
But what is striking is the absence of any detailed discussion about the costs of the massive arms buildup now under way, or of how such a buildup properly fits into the larger framework of American foreign policy and defense objectives. Mr. Reagan reminds voters that his administration is the architect of the current rearmament. And he wants more: a new ''star wars'' space defense program. Mr. Mondale, meanwhile, asserts that he would ''quarantine'' Nicaragua if that nation rejected US mediation efforts - a position that vividly underscores the degree to which the two candidates have staked out centrist, not totally dissimilar, positions on the issue of ensuring a strong US military posture.
The lack of a fundamental discussion on arms costs is unfortunate. The current buildup is enormous - close to $800 billion in spending over the past four years alone. Moreover, many of the new systems now coming on line, or planned for the future, such as the star-wars program, will cost taxpayers billions of dollars in additional outlays at a time when federal budget deficits are running $170 billion and up annually. The star-wars system alone will run in the range of $26 billion.
Why is a discussion of arms costs so important? Reports continue to surface about the serviceability of weapons - both strategic and conventional. Just this week, for example, Lawrence J. Korb said that one-fifth of the Navy's Sidewinder and Sparrow air combat missiles are ''unserviceable'' - that is, they can't be counted on to work. Mr. Korb can hardly be considered an antimilitary zealot. He's the assistant secretary of defense for manpower and logistics.
All of this - the magnitude of the arms buildup, in dollar terms, unreadiness in some conventional units, unserviceability of some weapons, and cost overruns - leads to one conclusion: A hard look at Pentagon spending is needed. Such an examination is in the best interest of the military. One cannot assume that public support for military spending is a bottomless well, especially without cost accountability. During the past two decades public attitudes about the military have tended to swing back and forth - from strong support to cynicism to support once again.
What is needed is something like the Truman Committee, which investigated the defense buildup during World War II. Talk about your crash defense program. The nation went from having a military that was almost nonexistent (it still had a horse cavalry) to having one of the largest forces of its kind in recorded history.
Looking back to 1941, President Truman later recalled that ''Washington was full of people seeking contracts, most of them sincerely desiring to be of help to the government, some seeking only their own selfish interest.''
The bipartisan committee investigating the defense effort was credited with saving billions of dollars - not to mention untold lives of US servicemen who might otherwise have used deficient equipment. Said Truman about his committee: ''We were not seeking headlines. We did not want publicity. We wanted only results.''
The scope of the committee's investigative work was virtually unlimited. It examined procurement. Construction. Contractors. Location of plants. And Truman took particular care in selecting committee members: ''I was determined that the committee was not going to be used for either a whitewash or a smear in any matter before it, but was to be used to obtain facts and suggest remedies where necessary.''
An arms buildup and a companion congressional scrutiny of the arms buildup are not incompatible. They go together. During World War II the United States turned out scores of new weapons systems that soon dominated the air, the land, and the seas. Most of them, thanks in large part to the Truman Committee, worked.