The official identified two “red lines” that could trigger an Israeli offensive. The first is tied to when Iran’s Natanz nuclear facility produces enough highly enriched uranium to make a nuclear weapon. According to the latest U.S. and Israeli intelligence assessments, that is likely to happen sometime in 2009, and could happen by the end of this year… The second red line is connected to when Iran acquires the SA-20 air defense system it is buying from Russia. The Israelis may want to strike before that system — which would make an attack much more difficult — is put in place.