A privately prepared, privately circulated report charges that U.S. drug control policy has refused to take on what ought to be its primary mission: chemical eradication of the coca crop in the Andean nations of South America. ''Few seem to grasp the fact,'' says the report by the National Defense Council Foundation, a small, conservative-oriented think tank, ''that without eradication, we will never be able to build enough treatment centers, correction facilities, hospitals and classrooms to handle the problem.''

The proposed solution: a new herbicide able to eliminate coca crops in Peru and Bolivia, the source of two-thirds of the world's cocaine. The United States should ''lead by example'' and eradicate its own marijuana cultivations at the same time. The whammy in this tough-minded, no-nonsense report is that the United States must have a ''contingency'' plan for ''unilateral'' action abroad if all else fails.

That is a red flag. For beleaguered leaders in the Andean countries, bowed down by economic dependence on the coca plant and political power by the drug cartels. For Greenpeace and other radical environmentalists. And for hard-charging drug czar William J. Bennett.

The report's authors are used to red flags. Retired Maj. F. Andy Messing Jr., the foundation's executive director, is a low-intensity warfare expert who often goes against the conservative grain (he opposed Ferdinand Marcos and criticized Nicaraguan contra tactics). His collaborator, Allen B. Hazlewood, spent 21 years in Marine Corps and Army counterinsurgency and denounced conduct of the Salvadoran war after five years as a U.S. anti-guerrilla adviser there.

Partly because Messing and Hazlewood have made careers of challenging desk-bound bureaucrats, Bush administration doors are closed to them on this issue. But unlike the policy makers, they have been out on the ground in the world's dangerous drug-producing regions, including Peru's Upper Huallaga Valley, where coca is cultivated and made into cocaine; Hazlewood spent 10 months there as the State Department's senior drug controller.

That provides a background for their attack on a policy that emphasizes education and domestic interdiction. ''The truth is,'' they write, ''that neither education nor treatment nor law enforcement ... can decisively affect the outcome of the drug war as long as drugs themselves remain dirt cheap and readily available.''

Their answer is Spike, the herbicide Tebuthiuron. Dropped by aerial bomb, it can wipe out the tough little coca plant, which has proved impervious to earlier means of eradication. U.S. officials have disdained a solution that would require the expense of substituting crops. ''If these countries want to eradicate, that's fine,'' Bennett told us.

But neither Peru nor Bolivia is a resolute drug fighter. The anti-eradication policy of left-wing Peruvian President Alan Garcia is being continued by his populist successor, Alberto Fujimori. Besides its economic impact, eradication threatens a clash with drug traffickers who have forged strong alliances with both the army and the guerrillas.

The threat of retribution, including sabotage, was clearly hovering over the refusal of Eli Lilly, Spike's developer, to sell it to the U.S. government. Dow-Elanco took over production when Eli Lilly quit, but it also refuses to sell to the government. These two companies have been pressured not only by the drug cartels and their armed allies but by what the Messing-Hazlewood paper calls ''leftist-co-radicals.'' Greenpeace has used its formidable resources to block the testing of Spike. Fujimori has taken up the chant, claiming that as an ''agronomist'' he opposes eradication on environmental grounds. In fact, the report cites evidence of the herbicide's safety and of environmental havoc on the Andean ecology wrought by cocaine production.

A wide ideological spectrum of congressmen agrees. ''Unless we have eradication,'' conservative Rep. Dan Burton (R-Ind.), honorary chairman of Messing's foundation, told us, ''we will not win the war.'' Liberal Rep. Stephen J. Solarz (D-N.Y.) described himself as ''very sympathetic to eradication efforts if we are prepared to help provide crop substitutes.''

The Bush administration claims its war is reducing supply and forcing up the price of cocaine. But Drug Enforcement Administration officials report no real drop in supply or price. Messing praises Bennett's vigor and determination but nevertheless contends that ''the war is not being won; it's just being lost more slowly.'' His call for eradication tests this nation's seriousness about fighting drugs.