MORDECHAI VANUNU….Chris Bertram notes that Mordechai Vanunu, who blew the whistle on Israel’s secret nuclear bomb program in 1986, was released today to surprisingly little blog commentary. Daniel Ellsberg, who is predictably sympathetic to people who expose government secrets, describes what happened to Vanunu in an LA Times op-ed today:

For that act ? revealing that his country’s program and stockpile were much larger than the CIA or others had estimated ? Vanunu was kidnapped from the Rome airport by agents of the Israeli Mossad and secretly transported back for a closed trial in which he was sentenced to 18 years in prison.

He spent the first 11 1/2 years in solitary confinement in a 6-by-9-foot cell, an unprecedented term of solitary under conditions that Amnesty International called “cruel, inhuman and degrading.”

Now, after serving his full term, he is due to be released today. But his “unfreedom” is to be continued by restrictions on his movements and his contacts: He cannot leave Israel, he will be confined to a single town, he cannot communicate with foreigners face to face or by phone, fax or e-mail (purely punitive conditions because any classified information that he may have possessed is by now nearly two decades old).

I’ll let others debate whether Vanunu is a traitor or a hero, but I’m curious about something else. Ellsberg correctly states that “to this day [Israel] does not acknowledge” that it possesses nuclear weapons, and this puzzles me. Why? It’s obviously common knowledge, so what’s the point of officially denying it?

Is it related to automatic U.S. sanctions if a country declares itself a nuclear power? Or something else?