FOR A NATION intent, as is the United States, on making a new foreign policy in a hurry, Pakistan offers an instructive, if sobering, case study. Thanks to the Soviet takeover of Afghanistan, Pakistan finds itself for the first time cheek by jowl with Soviet power and forced to ask whether its harboring of Afghan resistance fighters might lead to Soviet reprisals -- reprisals in the form of hot pursuit or the stirring of ethnic unrest or the reopening of an old Afghan border claim. Simultaneously, thanks to Indira Gandhi's return to power in India, Pakistan finds itself once again cheek by jowl with and Indian regime that feels an easy oneness with the Soviet Union and that rekindles all of Pakistan's old fears about dismemberment at Indian hands.

Enter the United States, looking for a sturdy local bulwark against further Soviet expansion in this most unstable, most strategic and most watched corner. Its eye rests on Pakistan, a traditional postwar ally whose nuclear policies and internal ways early cost it this administration's favor. The administration swallows its reservations on what it now sees as sub-issues in order to enlist Pakistan as point man on the main issue of containment.

Lo and behold, it turns out that Pakistan is a reluctant dragon. It is willing to take, on its own terms, whatever military and economic aid the United States offers, but not to act in a way -- for instance, by comforting the Afghan resistance -- that would antagonize the Soviet Union and expose Pakistan to a Soviet-Indian squeeze. The United States brandishes a "commitment" on which Dwight Eisenhower wrote a security guarantee for Paskitan, but the Pakistanis want to know just what it means now.

Fair question. There has been a lot of loose talk about Pakistan's taking up a position on the front line. But what for Americans is part of a grand strategy conducted far from home is for the pakistanis the life of their country. They look beyond pieces of paper 20 years old and words the president plans to use in his next speech and, trying to project one or two or five years ahead, they make the best reading they can of the disposition of Soviet and American and other forces on the ground and of the trends likely to affect the future uses of power.

This is what may be hardest for Americans now to understand: the circumstances that led Moscow to think i had a free pass in Afghanistan were years in the making and will take years to repair. Nothing that Jimmy Carter may say in the major Carter Doctrine" speech he is said to be planning will be as important as convincing people -- people everywhere -- that the United States is in the game for the long haul.