Sanctions for Iran, what about Israel?

The IAEA is aware of Iran's nuclear ambitions because Iran has talked about them and she's a signatory to the NPT. This honesty has got Iran nowhere and the UN Security Council recently voted to impose crippling sanctions against the country. Their president has said that Iran will take its nuclear programme underground and who can blame him?

Perversely, Israel's nuclear weapons capability is an open secret, but because Israel hasn't come out officially about its nuclear programme, the IAEA's hands are tied. The man who shone the spotlight on Israel's illegal nuclear programme is under virtual house arrest in Israel - he sought refuge in a church on his release from jail, after converting from Judaism to Christianity.

When it comes to Israel, the following applies

all animals are equal, but some are more equal than others

Why?