Israeli soldiers stand near a mobile artillery unit as it fires a shell from its position outside the northern Gaza Strip November 20, 2012. The U.N. chief called for an immediate ceasefire in Gaza on Tuesday and the U.S. Secretary of State headed to the region with a message that escalation of the conflict was in nobody's interest. Nevertheless, Israeli air strikes and Palestinian rocket fire continued for a seventh day. REUTERS/Darren Whiteside (ISRAEL - Tags: POLITICS CIVIL UNREST MILITARY)