Brussels — The first high-level discussion about the possible introduction of a new generation of highly sophisticated American-made conventional weapons in the Western alliance has also touched off a potentially lengthy debate over costs, contracts, and tactical ramifications.
Several European ministers and other officials remarked publicly or privately last week that any additional defense spending for such advanced systems under present economic conditions was ''unrealistic.''
They also displayed their irritation at the American domination of the military marketplace and emphasized that European industries would have to get a fairer share of any future weapons modernization program.
The emerging debate is expected to be a top agenda item in NATO for many years and has important implications for a host of allied and East-West issues.
It could further fuel the move in the United States Congress to reduce US forces in Europe and become an element in the agitation for reduction of nuclear armaments, a subject that could dominate the international political scene until the scheduled deployment of new NATO nuclear missiles late next year.
The semiannual meeting of NATO defense ministers in Brussels last week amounted to the initial European reaction to recent suggestions by Supreme Allied Commander Gen. Bernard Rogers stressing an upgraded conventional military force.
General Rogers' first public comments in September had stimulated a lively press controversy, especially in West Germany, where concern was high that the US might be paving the way for a dismantling of the nuclear umbrella over Europe.
US Defense Secretary Caspar W. Weinberger gave his NATO colleagues another glimpse of this emerging military technology. While they were officially cautiously receptive to further study, some of the other defense ministers privately expressed caustic concern about the concept.
Mr. Weinberger and other senior US defense officials gave journalists only the vague outlines of the new equipment still in the research stage for the most part. They said that they included advancements in laser, radar, and other areas ''beyond the fringes of classified material.''
They added that they would give NATO forces ''unprecedented precision'' in seeking out targets under all types of adverse conditions. General Rogers had also stressed that they could provide the ability to destroy enemy reinforcements and break the back of an invading force and lessen the need for nuclear weapons. Weinberger added that the study to be conducted in NATO would examine ''how the capacity of smaller land conventional forces can be enhanced.''
Other Western sources, however, indicated that such research included fiber optics and infrared technology, improved communications and intelligence, so-called ''brilliant weapons,'' biotechnology, and genetic engineering in the chemical and biological warfare field and even robotics.
''Brilliant'' weapons, as an example, would be better than the current ''smart'' weapons that home in on a target. ''Smart'' weapons need a soldier to release them, while their ''brilliant'' successor will not. The use of higher automation robotics also reduces the need for personnel.
At the same meeting, however, there were serious reservations expressed in many European delegations that the plans might result in another in a long series of costly purchases of American weapons by the US allies. During his press conference, Weinberger reacted testily, observing that ''this is not an effort to increase sales or any nonsense like that.''
West German Defense Minister Manfred Worner and his British colleague John Nott both said afterwards that there had to be a genuine two-way traffic in NATO arms procurement, with contracts for their own arms producers to supply weapons to the US.
This was the most recent occasion for European displeasure to arise at what some see as a reversal by the Reagan administration of previous efforts among the alliance to coordinate weapons development. A NATO drive to standardize allied weapons, reduce wasteful duplication, and enable European industries to win production contracts has slowed down since the advent of the Reagan team, analysts here say. The blame is put on the administration's free-market orientation, which feels that it is up to market forces and open competition, rather than government planning and intervention, to determine who should win lucrative arms contracts.
The end result, Europeans fear, is continuing large deficits and duplication in allied arms supplies. But any reluctance to commit themselves to this new round of costly defense spending seen as necessary by the United States could increase the pressure in certain US circles to reduce the American military presence in Europe.