Security was bolstered at the US Embassy in Baghdad and some staff members evacutated from the Iraqi capital as the Green Zone faced a threat from advancing Al Qaeda, State Department spokeswoman Jen Psaki said early Monday. She did not say how many of the 5,000-strong embassy staff, the largest in the world, were moved out to safer places, believed to be Basra in the south and the Kurdish capital of Irbil in the north.