Israel has massed thousands of troops along the border of the Gaza Strip and is threatening to invade unless the Palestinian Authority acts to prevent the firing of missiles at Israeli towns. Israeli Prime Minister General Ariel Sharon has instructed his military forces to show no restraint. In Gaza, residents were preparing for Israeli military action, speculating that it might begin when Secretary of State Condoleezza Rice, leaves after a short visit this week. Israel stopped all movement between the north, center and south of Gaza and prevented men between the ages of 18 and 35 from crossing the border into Egypt. Palestinian leader Mahmoud Abbas, who is in Gaza, made a televised speech over the weekend in which he reiterated his call for a single authority and a single armed force for Palestinians. Abbas said an Israeli invasion would “sabotage everything.”