Is the global arms trade out of control?; The Defense Industry, by Jacques S. Gansler. Cambridge, Mass.: The MIT Press. Weapons: The International Game of Arms, Money and Diplomacy, by Russell Warren Howe. Garden City, N.Y.: Doubleday & Co. $19.95.

Both these books help clarify why the 1980s seem destined to be the decade of big armaments. And from different angles, each suggests what could be done to change that.

Jacques S. Gansler, who has held senior posts in the Pentagon and with private US defense contractors, explains crisply and clearly here that "the weaknesses within the defense industry are . . . serious . . . because of the worldwide military environment -- the fact that the United States is significantly 'outgunned' by the Soviet Union, the large standing armies on both sides, the continued threat of nuclear warfare, and the vulnerability of the homeland."

Russell Warren Howe, a veteran foreign correspondent and student of the Washington scene whose earlier book (with Sarah Hays Trott), "The Power Peddlers" was a classic study of foreign policy lobbies, methodically maps out in this encyclopedic volume how human elements influence the vast and growing arms trade conducted by both governments and private merchants.

Mr. Howe's careful research and graphic writing illuminate such arcane subjects as lasers, beam weapons, spy satellites, and space warfare. He deals with more earthbound subjects as well, such as how gun traders large and small have spread the huge US arsenal captured by the communists in Vietnam to buyers around the world.

Both authors deal with the way in which America's NATO allies and other friends, such as China and Israel, have followed the superpowers into the cutthroat global arms competition, in which billions of dollars worth of military hardware is used each year to win friends and intimidate or crush adversaries.

Mr. Howe recapitulates such sensitive matters as Israel's apparently deliberate attack on the US intelligence ship Liberty in the 1967 war and discloses real or simulated Israeli preparations during the 1973 war to shoot down a USSR-71 Blackbird reconaissance plane that strayed too close to secret Israeli nuclear installations at Dimona.

Each book generally takes an analytical approach. Mr. Gansler carefully describes why he believes that if the US defense industry continues to rely mainly on the play of free market forces and to emphasize foreign arms sales over domestic defense, it will no longer be able to see the country safely through national emergencies.

Reagan administration strategists might well consider Mr. Gansler's recommendations on how the Defense Department could obtain at least an additional $3 billion worth of needed equipment and services each year without budgetary increases.

Civilian and military defense production could be better integrated, Mr. Gansler goes on to argue, showing how in some detail. The Pentagon, he asserts, has paid too little attention to minor firms and subcontractors, concentrating instead on scrutiny of such giants as Lockheed and TRW. The Defense Department also has neglected proper planning for production surges like the one that followed the Soviet invasion of Afghanistan.

Planners in the new Republican administration will find much grist for their defense and foreign policy projections in the Howe book, as well. The author explains, for example, why any new round of SALT (strategic arms limitation treaty) talks between the US and the USSR cannot succeed unless each side can be certain that neither could accomplish a first missile strike without retaliation. His treatment of SALT verification problems is well-informed and imaginative.

Both authors point out that, though over half the US defense budget is devoted to nuclear defense of the NATO area, a new regional or global war seems far more likely to start in the Middle East, Persian Gulf, or Indian Ocean. This requires new strategic thinking.

Perhaps most important, these books make it clear that the arms dealings of the US, the Soviet Union, Britain, and France (and possibly even Brazil) are getting increasingly out of control. Anyone thinking, writing about, or, better yet, trying to remedy this situation needs both books on his or her work table.