Israeli ground troops enter the Gaza Strip in this July 17, 2014 still image taken from video provided by the Israeli Defence Force (IDF) on July 18, 2014. Israel stepped up its land offensive in Gaza... more 
Israeli ground troops enter the Gaza Strip in this July 17, 2014 still image taken from video provided by the Israeli Defence Force (IDF) on July 18, 2014. Israel stepped up its land offensive in Gaza with artillery, tanks and gunboats on Friday and declared it could "significantly widen" an operation Palestinian officials said was killing ever greater numbers of civilians. Israeli gunboats lit up the sky with their fire before dawn while helicopters fired into the coastal enclave. Hamas fired mortar rounds at the invading troops and rockets across the border at the southern Israeli towns of Ashdod and Ashkelon. REUTERS/IDF/Handout via Reuters (GAZA - Tags: POLITICS CIVIL UNREST MILITARY TPX IMAGES OF THE DAY) ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO SALES. NO ARCHIVES less 
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Reuters | Photo By HANDOUT / REUTERS
Fri, Jul 18, 2014 8:09 AM EDT