The lame-duck Congress chose an odd way to cap a year in which concern over a possible nuclear war in Europe had approached a boil. It made nuclear war seem a bit more possible in Europe. Sen. Ted Stevens (R--Alaska) was the man chiefly responsible, with an assist from Sen. Mark Hatfield (R-Ore.)

Stevens, chairman of the Appropriations defense subcommittee, had won the support of the full committee last fall for an amendment reducing American troops in Europe to the 1981 level, the better to force the laggard allies to pony up more for their own defense.

But few observers think the Europeans would react to unilateral American withdrawals by paying more. Most, including me, think they would conclude the United States is tiring of its NATO burden, and turn more toward neutralism.

In any event, there is no denying that when you reduce conventional strength, you lower the "nuclear threshold," the level at which your defense must threaten to go nuclear in order to deter attack. It is precisely to bolster a strategy of "no-early-use" of nuclear weapons that NATO's American commander is urging Europeans to increase defense by an annual 4 percent.

The Reagan administration, oft-burned, hesitates now to talk in public about the "nuclear threshold," for fear it will be accused of abandoning Europe if that phantom level is raised and of preparing to incinerate the continent if it is lowered. Fortunately, other senators made the nuclear argument, and the Stevens unilateral troop cuts, questionable on several grounds, did not carry.

But some similar provisions were finally sustained. The United States has pledged to send 10 extra divisions to Europe in an emergency, but this can't happen unless equipment is prepositioned and unless the Europeans have ready the reservists to support our units. The $150 million planned for these prosaic but absolutely vital purposes was lost.

Stevens vehemently rejects the view, common among his critics, that he and his defense Appropriations subcommittee lack policy smarts. He attributes the arrows to turf jealousy in the armed services committees' staffs, and he locates the root of his difficulty in the reluctance of some of his colleagues to accept the discipline of the budget procedure. The budget resolution of last June instructed his committee to cut $8.7 billion in outlays, he said to me, but Armed Services, dealing not with outlays (current-year spending) but with authorization figures (for spending over a period of years), left him the tough part of the job.

As for the nitty-gritty, he says 1) it is more important to fund American reserves than German reserves and 2) his committee was ready to do more prepositioning, but the House was dead set against it.

Stevens has a point in complaining that his committee is called upon to do the budgetary dirty work and that turf rivalries rage --and not just among the staffs, one might add.

But the constant thrust of the defense effort in Europe should be to make war less likely, and therefore to make nuclear war less likely, by strengthening conventional defense. You do not have to think the Soviets are planning to attack in order to accept the importance of easing the anxieties that many Europeans live under (and vote under) and of removing from Soviet planners' minds any conceivable temptation. On such subtle but fundamental currents the integrity of the alliance rests.

As for Appropriations Committee Chairman Hatfield, he represents two impulses: to reduce the danger of nuclear war--his name, you will recall, is on the Senate's nuclear freeze resolution--and to force a reluctant Pentagon itself to come to grips with the need to reduce spending. The trouble here is that the measures at issue forced a choice, since the effect of paring conventional defense in Europe is to lower that theoretical nuclear threshold.

Hatfield supported the Mansfield unilateral troop cuts proposed in 1970. He saw the Stevens cuts, he told me, as a way to pump more defense out of Europe and to induce the Europeans to address pending hot-potato questions of tactical nuclear modernization. He did not, I think, have his eye on the ball.