THE REAGAN ADMINISTRATION sent another message to the dungeons of the world, this marked to the special attention of Latin America's political prisoners. It is, "Don't count on us."

They have known from the beginning that they were on their own. President Reagan is opposed to human rights as a policy. It is intervention in the internal affairs of another country, an affront to its sovereignty.

At the bidding of the White House, the Senate voted last week to lift the human rights conditions on the sale of arms to the military junta running Argentina. The proposition was put forward in an amendment of Sen. Nancy Kassebaum (R-Kan.) that Argentina is doing better on human rights violations and should be encouraged, if not rewarded.

The most conspicuous victim of junta policies is, of course, Jacobo Timerman, whose book, "Prisoner Without a Name, Cell Without a Number" gives majestic witness to 30 months of imprisonment without charges and torture without mercy. He was here recently to collect the Letelier-Moffet Human Rights Award, a prize that recalls another Latin American outrage which the administration wishes to forget. Orlando Letelier, a distinguished Chilean exile of the Allende years, was murdered on a Washington street along with an American citizen named Ronni Moffett.

Timerman said he was not bothering to lobby against unconditional arms sales to Argentina. "It won't matter," he said somberly, "The country is collapsing economically. Tanks and planes won't make the slightest difference." Ironically, the chaos created by the military strong men in Argentina was used by the administration as another reason why we should extend help.

Argentina is an excellent example of a country which ranks as a "friend" despite a striking record of hostility to our interests. During World War II, it provided haven for Nazis. Currently, it sells two-thirds of its wheat to the Soviet Union. It ignored the wheat embargo imposed by Jimmy Carter.

But somehow, according to Sen. Kassebaum, it is of strategic importance to us. It has a particularly repulsive record in human rights. Some 15,000 Argentines have "disappeared." They have never been accounted for Sen. Claiborne Pell (D-R.I.), with his usual timidity, proposed an amendment that would have demanded an accouting of the "disappeareds." But he decided to compromise with Kassebaum in favor of a mealy-mouthed expression of a "sense of the Senate" that Argentina really ought to provide information "as far as the government is able to" and list all those "disappeareds who have neither been released or brought to trial and who are being held at the disposition of the National Executive Power."

The critical passage, of course is, "as far as the government is able to," which is as close to exonerating the government goons as they could possibly wish. The number of "disappeareds" has declined. But according to Amnesty International, the rate of harrassments, detentions and other abuses has not.

About the only thing human rights advocates derived from the sorry afternoon's work was a gentleman's agreement, at Sen Edward Kennedy's instigation, that at the time of presidential certification of human rights progress, public hearings would be held.

Chile comes up this week. It is another example of a South American dictatorship which cannot offend us. U.N. Ambassador Jeane Kirkpatrick, who has demonstrated a special tenderness for iron-fisted anti-communists, recently made a sentimental journey to Santiago to certify the worth and merit of the Pinochet government and to normalize relations with it.

Just to show what her mission meant to them, the Chileans kicked out Jaime Castillo, a human rights lawyer, who had had the termerity to go into court and ask for redress for the Letelier family.

That expression of contempt is not expected to influence next week's Senate vote on repealing restrictions on military aid to Chile. We roll over when a friendly anti-communist regime spits in our eye. Chile has refused to extradite three high officials who were indicted by a grand jury in the murder of Letelier. Although some might see this as an affront to our national sovereignty, it is not in the eyes of the indulgent Reaganites.

We must not, you see, intervene in the affairs of a right-wing government. When it's the left, though, it's a different story. We must intervene, evidently in the affairs of Angola. The same day it voted to pat Argentina on the head, the Senate repealed the Clark amendment, which had prohibited CIA activity in Angola, a country which displeased us by choosing a leftist government over our chosen client, Jonas Savimbi.

And we will, apparently, intervene in the internal affairs of Saudi Arabia. At his press conference, the president, irritated at the suggestion that by selling AWACs to the shaky royal family, whose members, show a Shah-like greed for sophisticated military hardware, he might be creating "another Iran," retorted that there was no possiblity of a repeat catastrophe. "There is no way that we could stand by and see that taken over by anyone that would shut off that oil."

That sounds like military intervention. In other words, unpopular governments who are good arms customers are not to worry. Political prisoners can expect nothing but "silent diplomacy," which as Timerman said, means trying "to go back to the silence of the years of Hitler."