Defying a Palestinian Authority ban on public displays of weapons, about 1,000 people brandishing assault rifles and rocket launchers marched through Gaza City on Thursday and vowed to hold on to their arms. Members of the Al Aksa Martyrs' Brigades, fired into the air while their leaders made speeches insisting on the right to bear arms against Israel. "Brothers, don't ever give up your weapons," said a senior Gaza leader known by the nickname Abu Ibrahim. "We can't lay down our arms while Israel still occupies the West Bank, surrounds Gaza and controls our airspace and coastal waters, which means...