THE FALKLANDS AFFAIR is so different from the kinds of crises we have come to expect and fear. There is, for instance, not the slightest aspect of a bloody guerrilla struggle. The scene is a largely barren archipelago. There has been no repression, no injustice. There are no hills or urban warrens for the fewer than 2,000 victims to retreat to. Argentina took control within hours.

So many crisis scenarios anticipate a climax building within minutes, or at most a few days. Here the countdown has been stretched to an almost tedious couple of weeks. At the dock as the fleet departed Britain, there was a positively nostalgic quality: soldiers bravely sailing off to defend their country's honor, which unquestionably had been defiled. A carrier called Invincible, aboard it a prince: who would have been surprised to see, among those waving goodbye, Claudette Colbert?

Yet the costs of the crisis, for both Britain and Argentina, may mount. Britain's foreign secretary yesterday became the first casualty, resigning. His steadying hand had given Mrs. Thatcher her single international triumph, in Zimbabwe. The prime minister, under fire already for her economic policies, now must carry the additional burden of what many Britons see as an unspeakable affront to the national dignity. Whether the navy, having been restructured for other missions, can accomplish even its limited assignment of helping to restore British "administration" of the Falklands will be played out in slow motion in the South Atlantic.

The whole Argentine nation seems to be on an emotional jag. But there must come some sort of a diplomatic reckoning, if not also a military one, and after that the people will demand that the government return to the crushing cares it meant to flee by seizing the "Malvinas."

The worst of it is the contribution the seizure makes to a condition of global anarchy. The use of unprovoked force to resolve a grievance treatable by other means can be contagious. When something like this happens, and the aggressor is not held suitably to account, a great deal is lost in terms of future action by countries that have no connection with the conflict in question. The United States has a large and strong interest in seeing British administration of the Falklands recognize that interest and some of which do not.