Domestic drug abuse evolved in the 1960s and 1970s into a major concern of American foreign policy, the focus being to close down the international drug trade. In the 1980s, the depressing reality is that things get worse.

The Reagan administration claims major gains, including huge seizures, crop eradication and substitution programs, and law enforcement campaigns against, especially, the coca growers and distributors of South America and Central America. Still, from or through a score of nations, tens of thousands of tons of drugs a year flow into the fabulous American market. The supplies of cocaine may have quadrupled in the Reagan time. It gets cheaper and more plentiful, and, it is said, there are 5,000 new American users every day.

Only in Afghanistan, where the Soviet invasion has curtailed poppy cultivation, is the drug situation improving.

We Americans are more or less aware of the scourge of drugs in our society. We are not so aware of the scourge elsewhere. While coca brought income to peasants whose alternative was misery, Latins could live, uneasily, with the traffic. When local abuse started spreading and, in particular, when the profits created autonomous centers of power that defied government authority and even toppled governments, Latins were seized with true concern. Not just American nagging but their own alarm spurs their policy now.

For Americans, drugs are still seen mainly as a problem of personal lives or, at worst, class blight. But in countries with weaker institutions, drugs become a threat to the national integrity. This is so in Mexico, Colombia, Peru, Bolivia, Jamaica, the Bahamas and elsewhere. Persistent allegations made against the head of the Natioal Guard, one of whose accusers was found headless not long ago, indicate total rottenness at the core in Panama.

All this has produced some nasty inter- American political vibrations. For years, we Americans have had a tendency to feel the Latins were subverting us with their supply, but now some of the Latins feel we are subverting them with our demand. What they previously saw as a gringo problem for which we were ultimately responsible ourselves has become as well a Latin problem for which, in their minds, we remain ultimately responsible. The mood seems to be one of building recrimination and tension. The prudent expectation is that it will darken.

The Reagan administration has directed special rage at Cuba and Nicaragua for their suspected official complicity in the drug traffic. It is hard to believe no drug money flows into subversion or terrorism connected to those countries. Still, if Cuba and Nicaragua fell off the map, the stuff would keep coming through in immense quantities. That puts the United States in the situation of having to work out these rending problems with friendly countries that it is conducting a great deal of other difficult and necessary business with at the same time.

Politically, it is difficult for Latin leaders to ask their publics to make economic sacrifices and to accept unavoidably high-visibility anti- drug cooperation with the United States. They can see the relatively small size of American compensatory aid programs and the general inability to protect them against the personal and institutional violence of the drug traffic. They can hear frustrated Americans threatening to retaliate against the trade and aid of countries whose anti-drug cooperation is found wanting. Knowing of the United States' exploding and apparently insatiable demand, they can be forgiven for wondering if we are a reliable and compassionate ally in this deadly war.

The fight against drugs tends to stiffen those who get bound up in it -- to make them think that others are lazy and permissive and to turn them to ideas that not everyone is yet ready for. These ideas include using the military to intercept drug ships and planes; making the war against drugs not just one priority but the very highest priority; legalizing drugs to take the profit out of the trade; toughening the law or suspending certain constitutional protections. A greater agitation of rough- edged ideas like these is one price our society is probably going to have to pay for its past indifference and neglect.

Something else: a notion persists in many quarters of American society that a certain noncriminal or "recreational" use of drugs, mostly by adults but perhaps also a bit by kids, is permissible; anyway it's not the worst thing in the world. Many members of the educated classes prefer to concentrate their minds on the abstract horrors of nuclear war. But drugs are the worst thing in the world, and they're real.