THE MILITARY GANG that took over the Bolivian goverment in a coup on July 17 and has since been ravaging the country's frail freedoms has now turned with a vengeance upon the foreign press. Passing beyond the crude intimidation that is the stuff of journalistic life in many Third World countries, the military rulers in La Paz have declared that they will try Mary Helen Spooner, an American correspondent who has been working for London's Financial Times. The story for which she was arrested alleged that the new president, among others, was involved in the drug trade, and it reviewed certain episodes in the past of the interior minister, the head of the police. She is accused of libeling and defaming the country's leaders -- a charge leaning heavily on the pernicious sort of criticism of the foreign press that has seeped through the Third World in recent years.

We realize that many Bolivians have suffered greatly since the coup: there have been scores of killings, perhaps a thousand arrests and mass deprivation of rights. Nothing that has happened to the foreign press corps compares with those depredations, and, anyway, foreign correspondents take their chances when they go to places where the normal protections cannot be counted on. But none of this is justification for the harsh threat to Ms. Spooner.

It is common knowledge that the new Bolivian leadership includes some of the top dealers in the country's thriving cocaine trade. Informed Bolivians point out that one reason for the coup was the promise of the newly elected president to move against the drug trade. If the Financial Times correspondent was exposing further details of this traffic, then she was only amplifying a record that has already stigmatized the Bolivian military in the eyes of the whole hemisphere. The threat to bring her to trial will be taken as a desperation move and as a confirmation of the darkest allegations made about the makers of the coup.