IF PRESIDENT CARTER had been asked two years ago to resolve an argument between the defer-to-the-Third-world-majority crowd at the State Department and the show-we-stand-by-our-old-friends gang at the National Security Council and Defense, he would likely have gone with the former. That seemed the president's natural bent, and neither events in the world nor political currents at home had led him to question it seriously. But these things have shifted and so has the emphasis of the president's diplomacy. He now seems somewhat chastened, more cautious and traditional, more ready to value continuity, predictability and loyaly. It is by and large a sensible turn. The latest evidence of it is his decision to sell Morrocco weapons to use against the Polisario guerrillas in the Western Sahara.

There is a chance, of course, that Morocco will take the weapons and, as critics of the deal fear, ignore the administration's advice to negotiate an end to its Western Sahara involvement. The struggle there involves a Moroccan effort to impose its sovereignty on a small population that has not had the opportunity to register its own political will in an acceptable way. But there are some special reasons to believe that Morocco will not simply take advantage of the administration. The arms to be sent are evidently enough to let Morocco hold up its end, which has gotten heavier since its own attacks into the Western Sahara provoked Polisario attacks back into Morocco, but not enough to ensure victory. While Washington fiddled over the arms decision, Morocco burned, becoming more impatient but also having full occasion to learn that Washington does not mean merely to sponsor a wider war. It is not that the administration deliberately dallied to make its point. But effect may have been the same.

The Western Sahara is a desolate place with a nomad population unaccustomed to national frontiers and with a relentlessly drifting desert. It is unfortunate that King Hassen stumbled into staking his prestige and perhaps even his reign on what happens there. In any event, for Washington the issue is not so much the Western Sahara, whose future has evoked concern on the part of various worthy Africans. The issue is King Hassan. He has been a friend, in Africa as well as the Middle East, and it is worth showing him and others who may be watching -- and everyone is watching -- that United States values his friendship.