SECRETARY OF STATE Haig's return to Washington suggests he did not receive from the Argentines an offer he thought worth conveying in person to the British. This is too bad; but there are worse things than giving it your best shot, as Mr. Haig clearly has done, and falling short. One worse thing would have been to try to peddle to the British an Argentine position that was unprincipled and nonnegotiable. That seems to be what the generals in Buenos Aires had in mind for Mr. Haig to do. Argentina has insisted throughout on having its sovereignty over the "Malvinas" recognized all around at once. The secretary's consistent view has been that the sovereignty issue should be put off for negotiation later.

There is the heart of it. From the start of the Falklands affair there has been only one substantive issue: the attitude one should take toward the Argentine effort to assert sovereignty over disputed territory by force. True, many nations have acquired their territory in the past this way, but most of the countries of the world clearly decided after World War II not to condone that method any more. To indulge Argentine aggression in the Falklands would be to trample what is no less than the fundamental principle of contemporary world order. It would, moreover, have immediate and potentially vast practical consequences. Israel, for instance, may be contemplating asserting its sovereignty in the West Bank, Syria in parts of Lebanon, Turkey in Northern Cyprus and so forth. Such countries must be keenly watching whether Argentina gets away with its grab.

Fortunately, the argument of principle coincides with the argument of friendship. The United States, and not just this administration, is as close to Mrs. Thatcher's Britain as it is to any nation anywhere. There is no similar closeness to Gen. Galtieri's Argentina, even after the Reagan administration's geopolitical fancy is factored in.

During the Haig mediation, there was good reason for the United States to swallow criticism (from both the Argentines and the British) and to work for the best possible diplomatic access to both sides. But if Argentina has now made further American mediation pointless, then the administration will be free to take a position arising in the first instance from alliance considerations. It is not every day that this country gets to support both a principle and a friend.