Nobody is absolutely sure what is going on at the Nicaragua-Honduras border, except possibly the CIA, which is said to have 200 agents there. On your nightly news you can see wounded peasants--some are dead. But don't expect to find out from anybody in this government if the United States is involved.

It's no wonder the Reagan administration, beginning with the president, thinks "no comment" will suffice about events which, to the rest of the world, look suspiciously like a U.S.-backed armed assault on the Sandinista government.

They've gotten away with so much so far, they would be silly to be self-conscious now. After all, no Americans are dying.

Fifteen months ago, when The Washington Post published an article about a $19 million covert campaign to destabilize the Marxist regime in Nicaragua, the administration did not trouble to deny it. It was not then the taxpayers' business to know if they were providing arms, training and logistical support to anti-Sandinista rebels. Nor is it now that what is officially called "a spontaneous uprising" seems to be in progress.

Reagan's only deference to possibly adverse public opinion about sponsoring more bloodshed in an area that has more than its share was the postponement, during his December visit to Latin America, of joint Honduran-U.S. military maneuvers along the Nicaraguan border. The exercises were held last month.

Since the fighting began--and the scope, like everything else, is in doubt--all queries have been shrugged off. Secretary of State George P. Shultz put his brick in the stonewall when he airily told a congressional committee that it was a secret matter for the Intelligence committees.

The administration's message to Latin America is quite stark, even brutal. Go left, and we'll get you. Remember Chile.

Besides, if the president admits that we are subsidizing the raids, he could admit to breaking the law. The so-called Boland Amendment, passed last December, forbids him to supply military training, or advice . . . or support for the "purpose of overthrowing the government of Nicaragua."

But the only member of the administration to be challenged directly on the point, U.N. Ambassador Jeane J. Kirkpatrick, appearing on the "McNeil-Lehrer Report," told Rep. Michael D. Barnes (D-Md.), one of few congressmen still in town during the Easter recess and the only one so far to object, that "absolutely that no law is being broken." In her most withering manner, she reproached him for even suggesting it.

Like a lot of people, however, Barnes is not convinced. If we are not breaking domestic law, he says, we are violating the Organization of American States treaty, which forbids the subversion of any government in the area, for "whatever reason."

When it bothers to explain what looks like the flowering of the plot, the administration says that our purpose is not to overthrow the Sandinistas but merely to give them a hard time. Their real rationale, of course, is that if Nicaragua sends arms to the rebels in El Salvador, it must expect to get some back.

Kirkpatrick is ever ready to air her well-known view that any right-wing dictatorship is preferable to the left-wing kind.

Most recently, she told the American Legion that the only difference that counts between the Somocistas and the Sandinistas, by whom the Somocistas were overthrown, is that Somoza was friendly to the United States while the Sandinistas' national anthem has a line calling the United States "the enemies of mankind." The possibility that 40 years' of American support might have guided the lyricists is left out of the equation.

But at a meeting of the National Security Institute for Women at Fort McNair, Kirkpatrick limited herself to a disemboweling remark about the U.N. Security Council debate--during which several friendly nations voiced skepticism that the military actions now taking place were "spontaneous." She likened it to "gang rape," which may have jarred some members of her audience, but probably nobody at the White House, where they like strong stuff.

Whatever is happening in Nicaragua, the administration's cavalier refusal to discuss U.S. involvement only goes to show once again that Congress is no match for a strong-willed White House. When the Boland Amendment was being debated in December, Rep. Tom Harkin (D-Iowa) warned that Reagan would get around it. Harkin wanted to proscribe "any military activity."

But Rep. Edward P. Boland (D-Mass.), chairman of the House Permanent Select Committee on Intelligence, does not like to upset the CIA, and put over the loophole version. He assured the House that he would personally see to it that the situation "did not get out of control."

Now that it has, he is in China on tour. Only Barnes is left to complain that what is being done is wrong--it is against the law Congress thought it was writing.