Kabul 'Green Zone' tightened after attacks in Afghan capital

By Hamid Shalizi and James MackenzieKABUL (Reuters) - Afghan authorities are tightening security in the central area of Kabul housing foreign embassies and government offices after a string of suicide attacks that have caused hundreds of casualties and hit confidence in the Western-backed government.Two months after a truck bomb killed at least 150 people on May 31 in the biggest such attack since the U.S.-led campaign to oust the Taliban in 2001, a series of scanners and cameras have appeared a