On top of the huge pile of uncertainties in the world power struggle -- Poland, Afghanistan, Lebanon, the Persian Gulf, Central America and southern Africa -- the French election last Sunday heaped more puzzles.

Nobody knows how the new president of France, Francois Mitterand, can impose a Socialist regime on a society that remains profoundly conservative. Nor to what extent his victory will strengthen the neutralist assault on Chancellor Helmut Schmidt in West Germany.

So mere prudence requires the United states to reassess the Atlantic connection. That means thinking explicitly about two different global strategies that have already emerged implicitly in a series of clashes between Secretary of State Alexander Haig and the Defense Department under Caspar Weinberger.

A change in the geography and balance of world power provides the starting point for both strategies. The rivalry between the United States and Russia, which began in Europe and then shifted to Asia, now centers around the Persian Gulf. Though the Russians have been contained in both Europe and Asia, they have steadily increased both their nuclear and conventional military strength relative to the United States. At the same time, the United States has lost much of its competitive edge over such allied nations as Japan, Germany and France.

The Haig strategy continues, nevertheless, to emphasize allied solidarity. The secretary of state favors a joint buildup of U.S. and allied forces in both the conventional and nuclear domains. He seeks to enlist the help of the European allies in the Persian Gulf, and in applying pressure to such Soviet surrogates as the Cubans and the Libyans.

More important, once the military balance has been righted, Haig would work hard to achieve what the Europeans cheifly seek -- detente with the Soviet Union. Thus, in keeping with the European preferences, he laid out at the NATO foreign ministers meeting in Rome two weeks ago a timetable for beginning talks with Andrei Gromyko on arms control before the end of this year.

The Pentagon strategy has not yet been articulated. But it has deep roots in the isolationist tradition and the Pacific emphasis so dear to the Republican Party. It keeps cropping up in comments by Secretary Weinberger and his principal aides.

The United States, in the Pentagon view as I interpret it, is an insular power. It depends on the outside world for markets and for access to raw materials. A chief security requirement is protecting the sea lanes. Naval strength is critical in that respect. Equally important, besides a position in Europe, are footholds all over the rest of the world -- in Panama, Brazil and Argentina; in Egypt, Israel, Saudi Arabia, Turkey and Pakistan; in Japan, the Philippines and Taiwan; and in South Africa.

Restoring American military power has to be done rapidly and on a big scale. With allied help, if possible. But if the European allies are not prepared to shoulder responsibilities outside the Continent, then -- the theory runs -- the United States should not shrink from going it alone. Nor is there any urgency about coming to terms with Russia on arms control. On the contrary, the crucial matter is maintaining the right conditions for a sustained American military buildup.

Except for the occasional wrangles, the Reagan administration has so far been able to live comfortably with the two different strategies, but the time of grace is clearly ending. Beginning this week with the vist of Chancellor Schmidt to Washington, there will be mounting pressure to make choices.

The chancellor is on the ropes at home. Among the things he needs is a much stronger American commitment on arms control talks with Russia -- the better to face down the opposition to new defense measures now being led by former chancellor Willy Brandt within Schmidt's own Social Democratic Party.

My own feeling is that Washington should try to accommodate Schmidt by appointing an earlier date for the resumption of talks with Moscow. Schmidt remains the most important allied leader by far. If he were to fall, the Social Democrats would turn neutralist with a vengeance, thus blocking the way to any further strengthening of the military posture in Europe.

But if the Russians continue their relentless military expansion, and if the allies, while themselves unwilling to pick up the burden of defense, keep insisting on more American concessions to Moscow, then the United States will have to tilt toward the Pentagon strategy. Loath as many of us are to let the Europeans, and especially the Germans, fend for themselves, there are other and larger interests at stake. The United States has to look at those interests -- all the more so if the Europeans choose to turn their heads away.