THE EMBARGO on Cuba is back in a form lending itself to a step forward by the United States. A bipartisan Senate group led by John Warner (R-Va.) and Christopher Dodd (D-Conn.) supports a farm appropriations amendment to lift certain sanctions on the sale of food, medicine and medical supplies. It's a modest advance but a respectable one, and it ought to be enacted.

The argument over Cuba sanctions comes down to the contention that relief will profit not the deserving people of Cuba but their unchosen government. Grant that Fidel Castro will squeeze some advantage out of just about any move Washington makes on sanctions. The fact remains that the United States, by dealing in the substance of humanitarian care, sets itself up for charges of an anti-humanitarian stance. It is not so much high policy as common decency that argues for Americans finally to get out of the business of burdening ordinary Cubans' access to the basics of daily life.

The further argument for sanctions is that they make up a useful part of a pressure strategy for ending Fidel Castro's rule. But 38 years is a pretty good testing period, and 38 years of American sanctions have failed to do the dictator in. Nor is there the slightest likelihood that any but the most dependent nations will join the American anti-Castro front.

The alternative to pressure is a strategy of enticing Cuba into an ideologically corrosive engagement through the likes of personal contacts and radio broadcasts. It's worth attempting, and it's being done, but in honesty, it seems far from producing its intended result.

Mr. Castro survives by drawing on his police, international sympathy and Cuban nationalism. A hard American policy feeds the latter. Better for us, no matter what else we do, not to make it harder than the Communist system already does for the Cuban people to acquire the necessities of life.