Little by little, economic relations between the United States and the Soviet Union seem to be on the mend. The latest sign is the lifting of US export controls on the sale of American pipelayers to the Russians for the Siberian pipeline, the controversial project which caused such a strain in US relations with the Europeans a while back. Lifting of the curb makes economic - and diplomatic - sense.
Not that the Reagan administration was motivated primarily by foreign policy considerations. The fact is that the controls - in the form of requiring a Commerce Department export license for the product - were hurting the Caterpillar Tractor Company, which is in serious difficulties. Japan and other countries, which do not require export licenses, were stepping in to take business away from the US firm. About $90 million worth. There were thus practical domestic reasons for lifting this particular sanction.
What does this say about economic sanctions in general? They cannot always be counted on as an effective tool of diplomacy.
When the country imposing the sanctions is itself squeezed, the pressure to abandon the sanctions builds. Other countries rush to fill the economic vacuum and the ''host'' country is left with little but its sense of moral satisfaction. Which is not to say that economic sanctions should never be applied, but simply that they must be applied with wisdom and foresight. The fact that it is always easier to slap on sanctions than to take them off is further reason for caution.
In this case, even if Mr. Reagan may not intend lifting of the controls on sale of the US pipelayers as a diplomatic gesture, it does have the effect of improving the climate of US-Soviet relations. Add to this that US Secretary of Agriculture Block is in Moscow this week for signing of the recently concluded long-term grain agreement, and that in the fall the US-USSR Trade and Economic Council will hold a trade fair in the Soviet capital. It seems the Americans and the Russians, when it is in their mutual interest, can do business after all.