In the aftermath of the Soviet invasion of Afghanistan nine years ago, U.S. foreign policy-makers spent many sleepless nights wondering what the future would bring.

Now that the Soviets have finally packed up and headed home, the future is not only here, but it's still causing policy-makers worry lines.Among the latest concerns is that Afghanistan, already a principal opium producer, will be stepping up its supply of the illegal drug in the aftermath of the Soviet withdrawal.

Circumstances seem ripe. Afghanistan looks like a country that's just been ravaged by a violent nine-year conflict against the Soviets and remains embroiled in a civil war today.

Traditional agriculture - currently about half of prewar levels - has been made nearly impossible. And the temptation of quick money from growing opium poppies is likely to prove too great for the estimated 3 million to 5 million Afghan refugees expected to return to their war-torn homeland with no central government.

Not surprisingly, U.S. officials are bracing for the worst.

They are worried that amid a possible struggle among the various rebel factions, narcotics control isn't likely to be a high priority - despite longstanding U.S. warnings to the Mujahedeen rebels against producing and smuggling drugs to support their war effort against the Soviets.

But with the communist regime of strongman Najibullah expected to topple, most experts say the United States will have to wait until a central government is formed to start any meaningful drug eradication or crop substitution program.

There is reason for hope, however. A pilot program run by the Agency for International Development has been successful in encouraging some farmers to switch from poppy production to wheat and vegetables. It's hoped the program can be used throughout Afghanistan once a central government is created.

Said one official: "My sense is that the resistance leaders we work with are exceptionally sensitive to this and are aware that this is a domestic issue in the United States."

But in the meantime, the supply of illegal drugs from Afghanistan is sure to start increasing - with consequences on the streets of America.