THE SAMSON OPTION Israel's Nuclear Arsenal And American Foreign Policy By Seymour M. Hersh Random House. 354 pp. $23

SEYMOUR HERSH is no stranger to controversy. His previous books have probed the secrets of the My Lai massacre and its cover-up; Henry Kissinger's role in the Nixon administration; and the downing of KAL 007. He is a hard-driving, aggressive reporter. Now he has tackled one of the most difficult topics of all -- Israel's nuclear capabilities. Within days of The Samson Option's publication, Hersh was being threatened with lawsuits and the book was featured as front-page news in major newspapers.

Like his other books, this is a good read. And the topic has been avoided in the American press for far too long. New assertions leap from the pages; people talk, some even on the record, about the most extraordinary things; conspiracy abounds.

But, I kept asking as I read, is it true? That is the problem. Very few people know the full extent of Israel's nuclear program. I certainly do not, and therefore am unable to assess the accuracy of large parts of the book. One is left with the standard of plausibility and internal consistency, plus the credibility of sources.

On balance, I am inclined to believe most, but not all, of what the book tells. I have difficulty reaching a verdict on some of the most sensational points. First, a few of the highlights. Hersh convincingly describes the early years of Israel's nuclear program, placing emphasis on the role of Ernst David Bergmann, "the scientific father of the Israeli {atomic} bomb," and a name well-known to many Israelis, but unfamiliar to most Americans. The French role is also recalled. I was surprised to find Abraham Feinberg, a noted Democratic party fundraiser from an earlier era, talking openly of his part in helping to raise money for Israel's nuclear project, as well as lobbying the White House to ward off inspections of the reactor at Dimona.

On to the more juicy parts. Hersh places great emphasis on the primacy in Israeli strategic thinking of targeting the Soviet Union, not just potential Arab aggressors. And he does not just assert that Israel has a few Soviet cities in mind for purposes of deterrence, but rather he maintains that the Israelis have sought, and acquired, a capability to hit Soviet military targets. In pursuit of information on these targets, the Israelis have allegedly gotten hold of sensitive American satellite photography. Hersh, in fact, argues that the spy Jonathan Pollard was primarily after such targeting information. Even more extraordinary is his assertion that Israeli Prime Minister Yitzhak Shamir had some of this intelligence material transmitted to the Soviet Union.

The source for some of these allegations, it turns out, is the ubiquitous Ari Ben-Menashe, a one-time "signals intelligence expert" whose credibility on the so-called "October surprise" has been seriously questioned. Doubts concerning some of Hersh's points inevitably will continue until other, more reliable sources come forward publicly to confirm them. But on the basis of plausibility alone, I find it difficult to believe that Israel has developed a so-called "counterforce" capability against the Soviets. It makes little sense militarily, in contrast to a "city-busting" capability, which might make the Soviets think twice if they were considering threats to Israel. But why would Israel want to use any of its modest numbers of warheads and missiles just to hit a few Soviet military targets, thereby ensuring Israel's own destruction within hours? Far better, I would have thought, to leave the Soviets with the prospect that one or two of their major cities were at risk, full stop.

One of the most intriguing charges in Hersh's book is that Israel used "nuclear blackmail" to persuade the United States to begin the airlift of arms during the October 1973 war. There has long been a sense among American policymakers that providing Israel with conventional weapons was justified, in part, by the concern that Israel would otherwise feel compelled to rely excessively on a nuclear defense. This widespread view is rarely mentioned in policy deliberations, but I am convinced that it has had an impact on decisions.

Now, about the October 1973 war. Hersh claims that on the fourth day of the war, Oct. 9, Israel's ambassador, Simcha Dinitz, came to see Kissinger with a message that was tantamount to blackmail. Either the United States would immediately mount an arms resupply effort, or Israel might have to resort to nuclear weapons. Kissinger has denied that this occurred, but Hersh accurately (I checked) quotes from a respected American ambassador who heard Kissinger refer to "intimations that if they {Israel} didn't get military equipment, and quickly, they might go nuclear."

I was close enough to those events as a member of the National Security Council staff that I doubt that an explicit threat was made by Dinitz. We did know, around this time, however, that Israel had placed its Jericho missiles on alert. I did not know what kind of warheads they had, but it did not make much sense to me that they would be equipped with conventional ordnance. I assume others agreed. It was also conceivable that a nuclear threat might be made if Egyptian troops broke through at the passes. None of this had to be spelled out in so many words by the Israelis.

It is true that for one day, Oct. 9, there was a sense of panic among some Israeli leaders. By the end of the day, the tide was turning in Israel's favor, and Nixon had agreed to make up military losses. No one wanted to see Israel defeated, nor put in a position where it might consider using whatever nuclear capability it had. Without being told in so many words, we knew that a desperate Israel might activate its nuclear option. This situation, by itself, created a kind of blackmail potential. "Help us, or else . . ." But no one had to say it, and I do not think anyone did. The major decision to mount a full-scale airlift was, in any case, not made until Oct. 13, and then primarily because the Soviets had already begun direct resupply flights and a ceasefire effort had failed.

Kissinger's memoirs do use the word "blackmail" in conjunction with the meeting with Dinitz, and Hersh concludes that there "obviously" was a nuclear threat. But he does not give Kissinger's own reason for using the word blackmail. Dinitz, Kissinger recounts, asked in private if Golda Meir could make a secret visit to the United States to meet Nixon to plead for arms. Kissinger refused, arguing that such a proposal hinted at blackmail. In short, the United States would not be able to receive Meir in the midst of a war without responding favorably, and publicly, to her request for arms. Kissinger wanted to avoid putting Nixon in a position where his only choice would be to back Israel openly, thereby ruining any chance for the United States to act as mediator.

Take your pick of whose version is more credible. Kissinger's fits my recollection of the atmosphere of those dramatic days much better than Hersh's. If blackmail occurred, it was inherent in the situation, not the result of an explicit threat. And if it occurred, we were surprisingly slow to respond with a decision on a massive infusion of arms for Israel.

Apart from such questionable use of sources, Hersh weakens his impressive narrative by leaving a trail of minor errors. For example, he refers to Ephraim Evron as Effy, not Eppie, and gives him the title of ambassador to Washington 10 years before he actually had it. No big deal, but indicative of sloppy quality control by author and publisher. Likewise, Hashemi Rafsanjani is incorrectly elevated to the rank of ayatollah.

Hersh is angry at the United States for adopting a hypocritical stance toward Israel's nuclear program. He is correct that we have chosen to look the other way. He seems uncertain as to whether our government failed to understand what was going on, or whether it was instead a matter of high policy not to make a big issue out of something that we could neither reverse, nor condemn, given our own reliance on nuclear weapons and our perception that Israel did, indeed, face a potential military danger from its neighbors. He quotes Robert McNamara as saying: "I can understand why Israel wanted a nuclear bomb. There is a basic problem there. The existence of Israel has been a question mark in history, and that's the essential issue." Many who have faced Israel's nuclear option in the U.S. government would agree. Hersh, obviously, does not. Readers now have more information with which to form their own judgments. And for that, Hersh's book, despite its flaws, is welcome. William B. Quandt, a senior fellow at the Brookings Institution and author of "Camp David: Peacemaking and Politics," served on the National Security Council staff with responsibility for the Middle East.