President Reagan says he hasn't yet gotten to the matter of lifting the economic sanctions that the United States imposed on Argentina during the Falklands crisis. But what is he waiting for? The war ended more than three weeks ago with Britain's victory. Argentina could not be more poorly situated to resume the battle. The sanctions the United States imposed may have been of largely symbolic value, but there is no good reason to keep them on.

The official reason given for continuing them is that the United States is waiting for the Argentine government to express a "definitive position" renouncing further hostilities. That is also the position of the British, who want a "firm indication" that no element of the Argentine military will be tempted to have another go. To coax such an indication out of Buenos Aires, the British retain a few hundred Argentine prisoners.

But more is involved here than meets the eye. The Argentine threat to resume hostilities may look awfully threadbare, but the Argentines see it as their only card to induce the British to discuss their claim of sovereignty over the islands. Argentine nationalism and pride underlie this position, but it is also consistent with the United Nations Security Council's basic resolution, 502, on the Falklands/Malvinas conflict. Shortsightedly, in our view, the Thatcher government has turned its back entirely on that resolution's call for talks and on Britain's 17-year commitment before the crisis to work out with Argentina an agreement on the islands' future.

All of this only strengthens the case for unhitching American policy from Britain's. The United States does not have the luxury, as the British seem to think they do, of subordinating its relations with Latin America to other considerations. There was principled cause for the United States to back Britain in standing against the Argentine grab. But having done so, the United States is both required and entitled to take what steps are necessary to repair its Latin ties. At the moment the single most useful step it could take would be to lift its sanctions. Their continuation appears vindictive and pointless.