Secretary of State Alexander Haig didn't really want to hold a press conference last week, according to associates. He told them he had nothing to say.

Whereupon, he proceeded to declare war on international terrorism, to blame much of it on a "conscious policy" of the Soviet Union and to proclaim a reversal of American foreign policy priorities, with anti-terrorism supplanting human rights. "Linkage" would be applied to Soviet activities, worldwide. Haig was talking tough.

But he was right the first time. He really did have nothing new to say. And neither, for that matter, did President Reagan a day later, for all his harsh charges about the Soviets' lying, cheating and committing crimes in pursuit of a "one world" communist state. It was roigh stuff, but also, if you followed the Reagan campaign or the Haig confirmation hearings, entirely predictable.

So what are we to make of it? According to White House Chief of Staff Jim Baker, the new administration is going to be "realistic" in precisely the ways it thinks Jimmy Carter was "naive" about just everything from terrorism, to Soviet global ambitions, to human rights. No more special treatment for the Soviets, he added, by way of explaining the cold-blooded decision to withdraw Ambassador Anatoliy Dobrynikn's underground parking rights at the Department of State.

Well, I inquired over at the Soviet Embassy about how the signal was coming through and what reprisals might be expected for the removal of their ambassador's State Department perks. The response from a spokesman was, if not exactly mirthful, at least relaxed. Paraphrasing the president, he said: "We don't think revenge is worthy of us."

The point is not that the Reagan administration's approach to the threat of international communism may not be, in the end, a lot harder-headed than Carter's -- or even that it may not be a better approach. The point is simply that too much can be -- indeed, already has been -- made of last week's Haig/Reagan rhetorical outbursts.

Contrary to what you may have read, or heard, there is as yet no New Reagan Foreign Policy -- if by that is meant hard decisions on how broad principles, fundamental premises and general attitudes will actually be translated into action under the pressure of events.

On the contrary, those who would abbreviate the presidential transition period in the intersts of a quick and orderly transfer of power and advised to read the actual transcripts of last week's Haig/Reagan press conferences. It's been three months since Reagan knew he was going to be president and promised to "hit the ground running." But mostly what seems to be happening on the ground is power-struggling and scrambling and "reviewing" of issues that has looked wonderfully clear-cut during the campaign.

Reagan, for example, was still unable to say what he would do about the grain embargo, which is actually a pretty tough sanction against the Soviet Union, already in place and working a considerable hardship. The question of whether to retain draft registration, another measure imposed by Carter after Afghanistan and denounced by Reagan last year, was "something to be looked at further down -- I've only been here nine days."

The president clearly was not familiar with the nuts and bolts of the SALT II Treaty, another prime target in the campaign. At least some of the inequities and weaknesses he cited, including those having to do with verification, do not exist.

The Reagan analysis of the Soviets' grand designs on the world was, to say the least, too simple.Some would argue that it's thoroughly out of date. In any case, it is not an analysis that most European allies would accept.

And neither would the Europeans necessarily accept the Haig/Reagan policy of "swift retribution" for each and every terrorist act. Granted, this is a policy about which it is impossible to be precise in public, in advance of a particular incident. Granted, also, that the Soviet Union does have a heavy hand in support -- or exploitation -- of international terrorism.

But how do you "link" terrorism of suspected Soviet origin with, say, arms control negotiation in a way that effectively restrains the former while promoting the latter? Even tougher is the question of how you sell that proposition to the Europeans, who have a lot more firsthand experience with terrorism than we have -- together with a deeper yearning for detente.

All this is by way of noting a general rule: The first flings of foreign policy by almost any new administration are not usually the most reliable guide. In practice, the Reagan administration may be as tough as it sounds -- or tougher. Or, when it discovers what it's up against, "being realistic" may turn out in time to have been a little too simplistic or even (perish the thought) "naive."