Huffington Post - Egypt's most prominent reform advocate called on Sunday for President Hosni Mubarak to resign after the powerful military stepped up its presence across the anarchic capital, closing roads with tanks and sending F-16 fighter jets streaking over downtown. The army's show of force appeared aimed at quelling looting, armed robbery and arson that broke out alongside pro-democracy protests and have turned the cultural heart of the Arab world into a tableau of once-unimaginable scenes of chaos. The military made no attempt to disperse some 5,000 protesters gathered at Tahrir Square, a plaza in the heart of downtown that protesters have occupied since Friday afternoon. They have violated the curfew to call for the ouster of President Hosni Mubarak's regime, which they blame for poverty, unemployment, widespread corruption and police brutality. Read more .