-NUCLEAR PROGRAM: WHERE’S THE TIPPING POINT?…Diplomats confirm to the AP this morning that Iran has begun uranium enrichment at the “Fordo bunker,” a site deep under a mountain near the Shiite Muslim holy city of Qom. They say Iranian centrifuges are churning out 20 percent uranium that can be turned easily into warhead material. Western experts says uranium that pure is not necessary for power plants – and therefore can only be seen as a step towards a bomb. The new facility is buried deep underground on a well-defended military site and is considered far more resistant to airstrikes than the existing enrichment site at Natanz, limiting what Israeli officials, in particular, consider an important deterrent to Iran’s nuclear aims. Key questions raised here: where’s the so-called “red line” or tipping point for Israel – when that country would attack these sites? And for the U.S.? What does the new, better-defended site mean for any military effort to strike at the program? And – bigger picture: Are the sanctions and outside pressure driving Ahmadinejad and others to a harder line?