Secretary of Defense Caspar W. Weinberger may be doing a lot of listening this week. He will be in Brussels at a meeting of NATO defense ministers, which runs Wednesday and Thursday. In between plenary sessions and elaborate meals, he will probably hear much about two subjects: Western Europe's contributions to alliance armed forces, and the US Strategic Defense Initiative (SDI), or ``star wars'' program.
The formal purpose of Secretary Weinberger's trip to NATO's Defense Planning Committee meeting is to help outline the broad factors -- political, technological, etc. -- that will shape NATO military strategy for the next five years. He and other ministers will receive a first report on the effort, launched last December, to put new steel in NATO conventional defenses.
Last year, the United States' European allies were surprised by a rush of US criticism of their military effort. The chorus came mainly from Congress. In particular, Sen. Sam Nunn (D) of Georgia introduced legislation that would have yanked thousands of US troops out of Europe if NATO allies did not increase certain contributions to the common defense.
US allies were stung by the implication that their will was somewhat soft. They agreed to a significant boost in the NATO military construction budget, partly to provide shelters for US fighter planes. They began taking steps to increase ammunition stocks.
``Through 1990 one-third of our total defense funds will go for ammunition,'' said West German Defense Minister Manfred W"orner at a breakfast with reporters in the US earlier this year.
Clearly European NATO nations want to head off further US carping about their defense effort. That was one of the main reasons for Mr. W"orner's US trip in March.
Britain's defense budget this year devotes an entire chapter to detailing Europe's ``substantial'' NATO contributions. Since 1971, European NATO countries as a whole have increased their defense spending an average of 2 percent a year after inflation, notes the document.
Weinberger probably doesn't need much convincing. A just-released Pentagon report concludes that the NATO allies ``are making a substantial contribution to the common defense -- greater than is commonly recognized.'' For example, the report cites the fact that most European NATO allies have a draft to fulfill manpower commitments. And allies such as West Germany spend much on civilian projects that have military applications or value -- such as sewer lines to US air bases and support for Berlin.
Congress is another matter. Senator Nunn, through a spokesman, says he has not yet decided whether he will reintroduce his ``do better or we'll bring the troops home'' legislation.
Nunn is particularly concerned about NATO aircraft shelters and ammunition stocks, and there has been progress in those areas, says an aide. But it may not be enough progress. ``Why should the US have a 30-day supply of ammo if our allies have to give out in two weeks?'' says Nunn's spokesman.
Then there is the subject of SDI. At any meeting of defense specialists the pros and cons of SDI are debated at length, no matter what the offical agenda.
In public most allies say the program is necessary. In private they are worried. Western Europe is ``obsessed with SDI,'' notes Dr. John Steinbruner, director of foreign policy studies at the Brookings Institution.
Europeans are concerned that a space-based defense wouldn't be able to protect them. Soviet missiles, after all, could reach West Germany or Britain much more quickly than the US. US allies also fear SDI development could spur deployment of yet more offensive weapons.