Maybe the Israeli Embassy should demand that The Washington Post and The New York Times return its money. On the same day (Tuesday) that the embassy's full-page ads were disclaiming any responsibility for the Palestinian refugee camp massacres, front-page news stories in both papers were casting doubt on the denials.

The ads, which originated in the Israeli Cabinet, denounced as "blood libel" any suggestion that the Israeli Defense Forces bear "any blame whatsoever for this human tragedy."

But at the same time, the prime minister's office was acknowledging that the Israeli troops had deliberately allowed the Lebanese Christian militiamen to enter the two refugee camps, and that the Israeli Cabinet had given advance approval for the decision to let them in.

The ad went so far as to make heroes of the IDF, without whose intervention "there would have been much greater loss of life." But a Times story cited evidence suggesting that senior Israeli military and civilian officials knew of the killings some 24 to 36 hours before any move was made to stop them.

That same day, The Post reprinted on its op-ed page two editorials from Israeli newspapers. One of the editorials, from the generally pro-government Maariv, included this line: "(W)hoever gave permission for (the Lebanese militiamen's) entry into the refugee camps through the Israeli lines cannot hide behind the argument that he believed that they would behave with self-restraint."

Said the Haaretz editorial: "Even if it turns out that it did not occur to the IDF that the entry of the Phalangists to the camps would bring about these results, the fact that it allowed the entry of these paramilitary revenge-thirsty gangs points to an amazingly distorted perception."

The Israelis can deny only what they are not accused of: that their soldiers participated directly in the slaughter of hundreds of unarmed men, women and children in the refugee camps of Sabra and Shatila.

Israeli paratroopers posted outside the Sabra camp told a reporter for USA Today that they fired hundreds of flares over the camp to provide light for the killers. Said one soldier: "None of us thought of a massacre, but of cleaning out terrorists."

Now even Defense Minister Ariel Sharon has admitted that Israel helped to plan the entry of the Phalangists into the refugee camps and that senior Israeli army officers permitted them to remain there for at least a full day after suspecting the truth of what was going on inside. But Sharon, like Prime Minister Menachem Begin, cannot bring himself to acknowledge that he did anything wrong.

Well, the Israeli people know something is wrong. And the conscience-stricken reappraisal of what their country is all about may be the best thing to come out of the recent violence. After defending the June invasion of Lebanon (to clear a 25-mile buffer against PLO artillery) and the push farther into Lebanon (to protect the buffer) and the full- scale assault on Beirut (to break the back of the PLO and give peace a chance), Israel's friends, and an encouraging number of Israel's citizens, have stopped making excuses.

They understand the necessity of saying aloud what they have known all along: that it is possible to support Israel without supporting Begin; that Israel's security is more threatened than strengthened by the Begin/Sharon butchery; that defending every excess of the Israeli government in the name of solidarity will leave Israel defenseless and isolated in the world.

Which is not to say that the United States ought to encourage the ouster of the Begin government. That, as the Israelis keep reminding us, is a matter for them to decide.

The decision here could be a good deal simpler: that an Israel led by the likes of Begin and Sharon is not an Israel that the United States is bound to underwrite, militarily or otherwise.