Paris — As the Geneva summit approaches, France is signaling its distrust of superpower d'etente by making significant shifts in its own military strategy and spending. Defense Minister Paul Quil`es maintains that nuclear deterrence continues to be the French objective. He announced this week that France is developing a nuclear warhead to be ``almost invisible'' to enemy detection. This is being done, Mr. Quil`es says, in order to counter the potential threat posed by the development of space-based defense systems such as President Reagan's Strategic Defense Initiative (SDI or ``star wars''). The new warhead should be fitted to submarine-based ballistic missiles by 199 4, Quil`es said.
The French also want to put together a common Europe-based defense. The French made it clear for the first time last summer that they would rush to aid West Germany at the outbreak of a conflict. Then last week, President Franois Mitterrand agreed to commit France to participation in building a new European combat plane, reversing his earlier stand.
These shifts reflect long-term French defense goals. Large sums of money are needed to modernize the country's nuclear deterrent, which has long been the cornerstone of its independent foreign policy. Parliament passed a military budget last week that allocates about a third of total French military spending to nuclear weapons. The cost of this buildup pushes France into cost-saving cooperation with its European allies.
Political logic also encourages cooperation. The French are concerned about potential German neutrality. In a new book, Pierre Lellouche of the French Institute for Foreign Relations argues that France must contribute more to German defense in order to counter growing Soviet military strength. In another book, former Mitterrand adviser Regis Debray argues that a weak, divided Germany exposes France to pressure from both the Soviet Union and the United States.
Even after the Geneva summit, the French see superpower tensions remaining high. As Quil`es's speech shows, officials here feel that little can stop the Reagan administration from proceeding with SDI.
Of the Western European countries, France has expressed the strongest reservations about SDI. The French believe a space defense system won't work. In his speech, Quil`es listed a string of technological and economic reasons why a ``sealed defensive screen'' carried ``little'' credibility. He concluded: ``The sword always ends up triumphing over the shield.''
If French confidence in US military and defense initiatives are clouded, its perceptions of Soviet intentions are even darker. After meeting Soviet leader Mikhail Gorbachev last month here, President Mitterrand concluded that the new Soviet leader was changing the style -- but not the substance -- of Soviet foreign policy.
French officials say he spoke of arms control and claimed to want progress on the Middle East and Afghanistan. But Mr. Gorbachev promised nothing of substance, the officials said. He demanded that the French engage in bilateral nuclear negotiations and was immediately rebuffed. Mr. Mitterrand reportedly said that, with less than 200 missiles to the Soviet figure of around 9,000, France has far too small an arsenal to bargain.
Gorbachev also gave little indication he would soften on other issues. According to French officials, no concrete suggestions followed his statements of hope for resolution to conflicts in the Middle East and Afghanistan. And although he hinted that some increase in emigration for Soviet Jews might be considered, he made no promises.
The French do see signs of a thaw in superpower relations. But US-Soviet agreements apparently will not alter the French nuclear buildup. In addition to building its new ``invisible'' missile, in the next decade France will build two more nuclear submarines and a second nuclear aircraft carrier, its defense minister said. No money will be spared, Quil'es said, to assure that the French nuclear force remains credible.