THE GOOD news from the State Department is that the United States is stuck with 100,000 tons of surplus butter. The bad news is that the only customer for it is the Soviet Union.

According to my friends at The Washington Post, Robert Kaiser and Lee Lescaze, Secretary of State Al Haig is holding up the sale of the butter because he is afraid of sending the wrong signal to the Soviets.

I called my man at the State Department to find out what was happening.

"We're going ahead with the wheat sale," he said, "because we feel that it is now rewarding the Soviets for their aggression in Afghanistan. But if we also provide them with butter for their bread, they'll think we're not serious about our hard-line stand."

"That's good thinking," I said. "I've been to the Soviet Union and they can't eat their bread without butter on it."

"The secretary feels that our butter should only go to countries who play by our rules. If we sell the Russians the butter at the same time we sell them wheat, we would be giving up one of our biggest chips in any summit talks between Reagan and Brezhnev."

"I'm on Haig's side. What's the problem?"

"The problem is that Uncle Sam is up to his eyeballs in surplus butter, and if we don't get rid of it soon, a lot of it will go rancid. Therefore, the Agriculture Department wants to unload the butter on the Soviets now, while they're still interested in buying it. Agriculture is putting pressure on the president to make a bread-and-butter package deal at the same time."

"But don't they see that would be a wrong signal?"

"Agriculture isn't interested in diplomatic nuances. They've been buying up surplus butter from the American farmer at 10 million pounds a week, and if they can't unload it, they're going to have to eat it."

"Why don't we sell the butter to our friends and spite the Russians?"

"Because most of them have enough butter. And besides, if we glutted the market in the Free World with 100,000 tons, the price would tumble and the president would have every butter-producing NATO country on his back."

Suppose we sold the butter to the Soviets, but printed on each package in Russian that the proceeds from the sale were going to buy new weapons to prevent them from continuing their expanionist policies?"

"It's not that simple. Butter on the world market is now going for $1.05 a pound, a half of what it's selling in the United States. This means that not only would the Soviets have our American butter but they would be getting it 50 percent cheaper than what the American consumer has to pay for it. How can the president persuade Americans they have to give up butter for guns, when we're pratically giving the butter away to our archenemy?"

I said, "Wait a minute. I have a face-saving way out for you. The State Department announced we were going ahead with the grain sales because the Soviets didn't invade Poland. Why don't you declare you've decided to sell them butter because they didn't invade Yugoslavia?"

"We're way ahead of you," he said. "We're going to announce it next week."