Brussels — Key American officials in recent weeks have bluntly passed a message on to European governments and industrialists: Do not expect any significant expansion in transatlantic arms-production cooperation until NATO supports a United States plan for the deployment of a new generation of high-technology conventional weaponry.
American leaders have restated the country's commitment to improve such cooperation. But they have put the stress on future projects. And they have cast some doubt upon previous joint undertakings in this important economic sector.
Behind this stand is US national economic interest and the current campaign to tighten up on flows of sensitive technology.
West European governments and industries have been keenly interested because of the estimated 10-to-1 trade deficit they have with the US in such military supplies. But they have expressed reservations about the US stress on new technology because it is seen as another area dominated by the US. Still, emissaries from Washington have stepped up efforts to gain European acceptance, at the same time warning of possible diminished US cooperation.
The strongest such signal came at a conference here in early May attended by NATO government, military, and industrial leaders. Assistant Secretary of Commerce Lawrence J. Brady reminded the participants of the Reagan administration's two major preoccupations about such allied military contracts: the possible adverse impact on the US economy and jobs, and potential diversion of military technology to the Soviet bloc.
''This administration and industry [are] frankly concerned about the trade distortion of such cooperation agreements,'' Brady said. ''The onus is on American industry to protect its technology and markets.''
Defense Undersecretary for Research and Engineering Richard DeLauer was less menacing about the US willingness to cooperate. But he put the emphasis on far-ranging future prospects rather than immediate projects.
But he played down the approach of the previous administration to generate NATO allied cooperation around the concept of ''families of weapons.'' And he repeatedly looked ahead to possible cooperation on so-called ''emerging technologies,'' involving highly sophisticated electronic devices and conventional weapons aimed at hitting deep behind advancing enemy lines to break up an attack. This new generation of equipment has been promoted by US strategists but has received a cool reception from European NATO allies.
Some frankly regard such positions as another US attempt to divert attention from more immediate practical possibilities for cooperation and to press Europeans to accept new purchases in an area dominated by US producers. Speaking before another high-level conference at allied military headquarters near Brussels recently, Giovanni Agnelli, chairman of Fiat in Italy, complained about ''roadblocks by the Reagan administration'' on the two-way street of alliance arms cooperation. ''We should stay away from grand designs,'' he said.
Many other European and even US participants at these recent conferences were just as discouraged about the US attitude to such joint ventures.
A former high-level US official deeply involved in such efforts under the Carter administration said ''if we can't agree maybe we'll have to go back to strategic nuclear superiority'' for the main alliance deterrent.
But these and other US officials have taken great pains to convince Europeans of both the practical and strategic rationale for this position. They argue there may be a need to restrict technology transfer from the US to its allies because of the threat of diversion to the Eastern bloc. And while DeLauer and others were trying to convince various allies of the industrial and military justification for a defense based on sophisticated technology, other US leaders were explaining the new US policies in this emerging area.