The navy remained on high alert Tuesday, amid intelligence assessments that additional explosive devices aimed at striking its vessels are still floating out at sea.A senior navy officer said that ships were conducting patrols along the Mediterranean coast, searching for the bombs that contained between 15 to 20 kilograms of TNT.The detonator of the two that washed ashore on Monday evening were cellular phones attached to explosives and wrapped in waterproof material, which means that the Gazan terrorists would have needed to keep an eye on the barrel to know when to detonate them.Deputy Chief of General Staff Maj.-Gen. Benny Gantz said that the attempt to strike at navy ships was part of the terrorists’ efforts to find new ways to attack Israel due to the effective blockade of the Gaza Strip.“The incidents at sea demonstrate the difficulty terrorist groups have in carrying out terrorist attacks,” Gantz said. “We are closely following the developments and will continue searching the area.”On Monday, a navy crew shot at a barrel off the Ashdod coast that looked like the explosive devices that washed ashore on Monday. The crew later discovered that the barrel was lost fishing equipment.Police were expected to resume searches for additional explosive barrels after sunrise on Wednesday. Searches were temporarily suspended at nightfall. The public is being asked to stay off the beaches from Ashdod to Zikim for a second day running. Earlier on Tuesday, Cmdr. Bentzi Sao, head of the Israel Police’s Operations Branch, held a situation evaluation meeting that was attended by intelligence officials and representatives from the navy.Sao announced at the end of the meeting that officers would continue the searches, backed up by police helicopters and patrol boats.Police patrols on land, air and sea will continue to be beefed up in coordination with the navy, and mounted police will maintain an increased presence on the shoreline.The emergency 100 police lines will be staffed with more operators over the coming days.The public has been asked by police to remain vigilant and report any suspicious objects.The navy first learned about this new threat on Friday, when two explosions were heard by crews of navy ships patrolling the Gaza coast. Palestinian fishermen are allowed to venture 6 km. from the coast. Three terrorist groups – Islamic Jihad, Popular Resistance Committees and Fatah’s Aksa Martyrs Brigades – claimed responsibility.On Tuesday, the three groups again claimed responsibility for the attempted attack.On Monday, an explosive device washed ashore in Ashkelon and in the evening a second one was discovered in Ashdod. Both were destroyed by police sappers. “We believe that there are more barrels out there and have taken the necessary precautions,” the naval officer said.According to the officer, Palestinian terrorists rely on fishermen to assist in attacks and it was possible that the barrels were dropped into the sea from fishing boats. Since the devices did not have navigation or motor capability they also threatened civilian ships.