Hamas has seized control of all the smuggling tunnels under the Philadelphi Corridor in southern Gaza and has been moving additional arms into the Strip since Operation Cast Lead ended on Sunday morning. During the three-week operation, the IDF destroyed 80 percent of the 300 tunnels that Hamas is believed to have dug under the 14-kilometer stretch of land separating Gaza and Egypt. Some of the tunnels were not destroyed - like the one that was filmed by foreign media on Wednesday - out of humanitarian considerations. Several tunnels have pipes that transfer fuel from Sinai to Gaza. The concern in the IDF was that if it bombed such a tunnel, a huge explosion would result - possibly also on the Egyptian side - and civilian casualties. The IDF was also concerned that if a fuel tunnel were bombed, Hamas would respond by attacking the Nahal Oz fuel depot where there are gas canisters and fuel tankers, which if detonated would cause major collateral damage in Gaza and Israel. The tunnels in Rafah are usually run by local Palestinian clans, and Hamas's decision to take control is believed to be part of the group's attempts to reestablish its regime in Gaza. Hamas can now decide what is smuggled into the Strip and give priority to weapons and explosives. On Wednesday night, CBS News reported that the US Navy had intercepted an Iranian ship in the Red Sea carrying arms allegedly on their way to Gaza. Israel is concerned that Iran will try to transfer long-range Fajr missiles to Hamas capable of hitting Tel Aviv. Also on Wednesday, Hamas commandeered the trucks carrying humanitarian supplies into the Gaza Strip as part of its effort to show that it is providing for the Palestinian people. Defense officials told The Jerusalem Post on Thursday that Hamas had also taken over a mental hospital in Gaza City and had kicked out the patients to use the facility as a jail for Fatah supporters. The officials said Hamas was concerned that Fatah would try to take advantage of its weakened state and attempt to take back control over Gaza. During Operation Cast Lead, Hamas imposed curfews on predominantly Fatah neighborhoods and executed any Fatah member seen on the street. Also on Thursday, Amos Gilad, the head of the Defense Ministry's Diplomatic-Security Bureau, was in Cairo for talks about Gilad Schalit and the new anti-smuggling mechanism. The new mechanism Israel had set up with the Egyptians to counter the smuggling of weaponry and explosives into the Gaza Strip consists of three layers - intelligence cooperation, obstacles in Sinai and the deployment of new tunnel-detection technology along the border. Defense officials said Gilad would likely travel to Egypt every other week to oversee the mechanism's effectiveness.