The Kerem Shalom crossing, which was targeted by Hamas in a double car bombing over the weekend, will likely remain closed until after Pessah, which ends on Saturday, senior defense officials said Monday. Last Saturday, in what has been described as one of the most ambitious attacks in recent years, Hamas infiltrated two jeeps - packed with 300 kilograms of explosives - into the Israeli side of the crossing and detonated them next to an IDF watchtower and a group of soldiers, 13 of whom were injured. Kerem Shalom is the main conduit for humanitarian aid transferred from Israel to the Gaza Strip. The officials said that Defense Minister Ehud Barak was scheduled to hold a security assessment towards the end of the week to determine the continued operation of the crossing. The attack against Kerem Shalom followed an attempted infiltration into the crossing last Thursday and an attack against the Nahal Oz fuel depot the week before, in which two Israelis were killed. "The crossing will remain closed as a punitive measure and until the security there is improved," one official explained. Also Monday, Hamas spokesman Abu Jandal threatened to carry out harsher attacks against the crossings. He told a newspaper linked to Hamas that previous attacks on Gaza-Israel crossings Israel were just "practice." Abu Jandal described the recent attacks as "a walk in the park" and said upcoming attacks would be harsher. Israeli defense officials said the IDF was preparing a plan to bolster the security at the crossing that would likely include the deployment of additional concrete barriers to block sniper and mortar fire and make it more difficult for an infiltration.