Two barrels packed with 15 kg. of explosives each washed up on beaches in Ashdod and Ashkelon on Monday evening, in what security sources said was a carefully planned and coordinated terrorist attack emanating from Gaza and targeting Israeli ships, ports and naval bases.Southern District Police launched a massive search of the coastline in the area, backed by helicopters, mounted police and volunteers, and ordered the public to avoid all beaches between Ashdod and Gaza until further notice, fearing that more explosive barrels could turn up.The Shin Bet (Israel Security Agency) was investigating the discovery of the barrels, with a particular emphasis on the detonator and type of explosives.On Friday, a number of explosions were heard off the coast of the Gaza Strip, likely caused by additional devices that were thrown out to sea. Three terrorist groups – Islamic Jihad, the Popular Resistance Committees and Fatah’s Aksa Martyrs Brigades – claimed responsibility for the blasts.Officials said the bombs may have been meant to act as naval mines, detonating upon contact with a ship.Defense officials said Palestinian terrorists have been trying for years to strike at Israel Navy ships that patrol along the Gaza coast.“The terrorist groups have difficulty carrying out attacks due to the blockade on Gaza,” one official explained. “This is their way of trying to bypass the blockade and carry out an attack.”The incident began when fishermen on Ashkelon’s Hofit beach noticed the barrels and contacted police.A bomb disposal team under the command of Ashkelon police chief Dep.-Cmdr. Haim Blumenfeld neutralized the bombs, and closed off the beach for 500 meters in each direction.A few hours later a second barrel washed up on Ashdod’s Hakashtot beach and was discovered by an Ashdod municipal security officer on a routine patrol. A police bomb squad was called out to the scene, and detonated the device in a controlled explosion.“Police are continuing to assess the situation to maintain publicsafety,” police spokesman Micky Rosenfeld said. “We are asking thepublic to be extra vigilant and to stay on the lookout for anysuspicious objects.”If a suspicious object is spotted, members of the public are urged to contact police immediately.In the hours following the incidents, Southern Police District chiefCmdr. Yohanan Danino held a situation analysis meeting with policebrass, and ordered an increase in police numbers along the southerncoastline.Police boats have increased patrols, while mounted police and special patrol units will beef up their presence on beaches.