The Israeli prime minister's participation in the nuclear conference organized by U.S. President Barack Obama would have had immense importance. On a symbolic level, it's the first time Israel has been invited as a regular guest to a select, prestigious nuclear forum, effectively granting it recognition as a significant player in this very delicate arena. And there could be no better opportunity for Israel to win global legitimacy for its nuclear program. From a practical perspective, it will be the first time the "good guys" will have convened to address nuclear terrorism, perhaps the greatest nuclear-related threat our generation has to confront.

When the idea of such a conference was first raised, organizers told their Israeli colleagues that they would prevent a "nuclear ambush" against Israel because it has not signed the Nuclear Non-Proliferation Treaty. They said the summit's raison d'etre is establishing a new nuclear forum, parallel to but not replacing the treaty, to include in the global nuclear dialogue the three nuclear nations that have not signed it - Israel, India and Pakistan. Although organizers have no control over what their guests will say, they have control over the wording of the final statement, which could be drafted in consultation with Israeli officials to prevent any surprise on Jerusalem's part.

Benjamin Netanyahu's stunning decision not to take part in the summit, purportedly after being told that a number of Arab leaders would vilify Israel's nuclear policy and refusal to sign the treaty - a sort of Arab ritual at international forums - is regrettable and does not serve Israel's interest. The decision stems from fear, lack of trust and a sense of isolation - all hallmarks of irrational decision-making.

Even if Arab leaders do raise the issues in question, no one will take them seriously. Everyone knows that Israel, like India and Pakistan, cannot for legal and political reasons join the treaty as nuclear countries. And for their own strategic reasons, they can't join it as non-nuclear states, either. For each, signing the treaty would be perceived by its enemies as relinquishing key strategic advantages.

Let there be no doubt - Israel's policy of nuclear opacity is perceived by many the world over, including its best friends, as a political anachronism that is hard to swallow. To them, the problem is not the question of Israel having nuclear capacity, but the country's refusal to acknowledge it. The more Israel is viewed as a cautious, responsible nuclear nation, the harder it is to accept its policy of opacity as appropriate.

Opacity is widely perceived as concealment, an act of covering up a secret that cannot be revealed to the public. Today, however, the secret is known to all, so it's unclear why it must remain wrapped in ambiguity. In a world demanding that Iran speak the truth over its nuclear activity, ambiguity is seen as a bizarre relic from the past.

If Israel's prime minister feels he cannot uphold the country's opacity policy at a relatively friendly international forum, it seems this policy is in real trouble. If he is worrying about stumbling into a nuclear ambush and cannot rely on understandings on nuclear issues reached with the U.S. government, it seems Israel's diplomatic crisis with Washington is much deeper than we had imagined.

The writer is the author of the book "Israel and the Bomb." His forthcoming book, "The Worst-Kept Secret," will be published in the United States in September.