Several senior West German politicians on both the left and the right have started thinking seriously and speaking out about removing nuclear weapons from Europe and revising NATO's nuclear strategy, marking a new turn in the growing challenge here to Western defense and disarmament policy.

Building on months of popular unrest about nuclear weapons, the parliamentary defense experts of West Germany's three main political parties have each floated proposals in recent days arguing that America's nuclear stockpile in Europe of about 6,000 warheads could be reduced or eliminated if a balance in conventional forces between NATO and the Warsaw Pact were achieved.

The idea of trading the West's nuclear potential against a more evenly matched field of conventional forces in Europe is as old as the Atlantic Alliance itself. But more than 20 years have passed since the last major open debate here about nuclear doctrine.

Horst Ehmke, a leading Social Democratic member of parliament, along with some major West German newspapers have urged the chiefs of the 16 member governments of the North Atlantic Treaty Organization to use the summit meeting here next Thursday to authorize a study of a new NATO military strategy.

The apparent start of a new strategy debate in the United States is cited by the West German legislators as giving sanction to at least semiofficial attacks on existing alliance doctrines. Often mentioned are an article in the spring issue of Foreign Affairs magazine by four former high-level U.S. officials calling on NATO to adopt a "no first use" doctrine on nuclear weapons and a paper by Sen. Sam Nunn (D-Ga.) urging reduced reliance on nuclear deterrence in Europe.

So far, however, the Bonn government appears opposed to a rethinking of NATO doctrine, worrying that this could jeopardize U.S.-Soviet negotiations on nuclear weapon. West German Chancellor Helmut Schmidt, in an interview last week, dismissed as unrealistic proposals to try to bring about nuclear disarmament by building up NATO's conventional forces.

In tanks and artillery, the Warsaw Pact outnumbers NATO by about three to one, according to Western estimates. West European governments historically have declined to pay the enormous costs that would be necessary to attempt to catch up, preferring to rely on U.S. nuclear weapons as a deterrent to Soviet attack.

By seeming to reconsider this strategy, some German legislators may well be hoping to mute opposition to the government's defense policies and show the high costs of opting for alternatives.