How deep is the West's pipeline split?

Just a few weeks ago, President Reagan told reporters that disarray in the Atlantic alliance had been largely ended thanks to the work of his administration.

Then came French and Italian moves to defy American-imposed restrictions on gas pipeline equipment for the Soviet Union, talk of a steel ''war'' between the US and Western Europe, and speculation that the allies could be facing their worst crisis in relations since World War II.

''Crisis'' is an overworked word which may in this case be overly dramatic. As American officials point out repeatedly, areas of common interest outweigh differences among the allies. But there is clearly more trouble in the alliance than President Reagan has been publicly willing to admit. Instead of the kind of East-West confrontation which the Reagan administration focused on at the outset , it now has a series of West-West confrontations to cope with.

At the heart of much of the trouble are apparently fundamental differences between the Reagan administration and its allies over how to deal with the Soviet Union. Whereas many Europeans see East-West trade as a means of moderating Soviet behavior, the Reagan administration seems to think that much of this trade simply strengthens the Soviet Union's military defenses.

US Treasury Secretary Donald Regan put this view starkly in an interview on the CBS television program ''Face the Nation'' on July 25: ''We definitely have a hostile threat from the Soviets, and as far as we're concerned, anything that's done to improve the Soviet economy . . . will eventually hurt us and could harm us. . . . '' Regan was referring to President Reagan's decision last month to widen restrictions on American technology going to the projected Soviet-European gas pipeline.

Under the leadership of Secretary of State George P. Shultz, however, the state department is now reassessing every aspect of US economic relations with Europe in an effort to establish priorities and find areas where both sides can compromise. Officials indicate that if agreements are not found on a wide range of issues, ranging from steel to agriculture, the word ''crisis'' may begin to apply.

A top priority, as state department officials see it, is to lower the level of rhetoric. State deparment experts here conclude that European leaders, concerned about economic recession and unemployment, have been too inclined the blame the US for many of their economic problems. And these experts say they see two dangers if talk of a divorce in the alliance is allowed to continue:

First, a possible growth in isolationist sentiment in this country, based on a view that the European allies are not doing their part to counter the Soviets. Second, if the Reagan adminstration, for its part, is viewed by West Europeans as unyielding in its attitude toward the Soviet Union - and now even engaged in economic warfare against that country - the anti-nuclear movement in Europe might gather more steam and undermine the allied decision to begin deploying new nuclear weapons in Western Europe in 1983.

Despite the public perception that the two side are locked in crisis, one state department official argues that progress has been made between the US and West Europe on the issue of Western trade, at the undersecretary of state level. The official further contended that a significiant first step toward an understanding on the use of subsidized credits for the Soviet Union was achieved at the recent Versailles summit meeting.

Meetings of the US with its major trading partners scheduled for later this year in Geneva, this official said, offered the prospect for expanding multilateral trade agreements under the General Agreement of Tariffs and Trade (GATT). Greater cooperation on trade and high technology is possible, the official added.

But on one issue, President Reagan is clearly not in the mood to be compromising, and that is in pursuing his decision to impose restrictions which might delay the construction of a 3,500 mile natural gas pipeline between the Soviet Union and Western Europe. He is said to believe that this will create a dangerous Western European dependency on Soviet natural gas. Moreover, the President is said to be convinced that the Europeans are, in effect, still subsidizing the Soviet economy at easy interest rates. Most important, he hews to the view that the Soviets are largely responsible for the repression in Poland and must be made to pay for that.

In the view of some conservatives, the state department is all too inclined to look for compromise with the West Europeans. But even in the State department , officials who opposed the decision to widen restrictions against the gas pipeline argue that there is plenty of fault to be found on the European as well as the American side of the Atlantic.

''The Europeans are not just innocent victims,'' said one high-ranking state department official.

''The Europeans got away with murder on steel,'' the official said. '' On agriculture they pushed us pretty hard, and we have not done anything painful to them in agriculture.''

''No one I know in the adminstration thinks the pipeline is a good idea,'' he added.