Israel still wants a truce with Hamas, and believes that Hamas is also interested in resuming the cease-fire, defense officials insisted Thursday night, even as Kassam rockets continued to fall around southern Israel. As a result of the salvos, all the border crossings with Gaza remained closed to deliveries of fuel and other essentials. "We are interested in continuing the cease-fire, but we will act in every way to defend our soldiers," a senior defense official told The Jerusalem Post, a day after the IDF made the second incursion into the Strip since the cease-fire began in June. "We believe elements on the other side also wish to continue the cease-fire," the official said, adding that the rocket attacks Thursday were the terrorists' response to perceived Israeli violations of Gazan territory. "The other side is saying, you [Israel] entered Gaza and killed 11 of our fighters [in the past two weeks]. They are trying to exact some sort of price tag for that," the official said. Asked if Israel was planning on calling off the cease-fire, the official said, "there is no one line here, the situation is very dynamic. We have to make a [daily] decision on how to respond to events." But John Ging, who heads the Gaza operations of the United Nation's Relief and Works Agency (UNRWA), said that Israel's closure of the crossings, which has lasted for eight days, is playing into the hands of those who want violence to continue. "We acknowledge the security challenges. But these are challenges that have to be overcome, otherwise we hand the agenda over to those who fire rockets and that is a concession that should never happen," he said. As a result of the closure, as of Thursday night, he said, UNRWA had run out of food. It provides basic staples of flour, rice, sugar, lentils and powdered milk to 750,000 refugees, out of the 1.4 million people living in Gaza. Speaking in Brussels, UNRWA head Karen AbuZayd said it was unusual for Israel not to let basic food and medicines in. "This has alarmed us more than usual because it's never been quite so long and so bad, and there has never been so much negative response on what we need," she said. "We have hundreds of containers waiting in Ashdod Port, holding such simple things such as the wool and the yarn for vocational training centers or centers for the visually impaired to make some money," she said. "We were told these are not humanitarian supplies." In Gaza, a United Nations flour warehouse that was full early last week now stands empty. Another warehouse holds just a few crates of lunch meat and space usually filled with oil and powdered milk is taken up by air conditioners for medical centers yet to be built. The low level of supplies that have been brought in over the last year has prevented UNRWA from building up large reserves. "The closure of the last seven days had depleted the meager reserves we had," Ging said. By Thursday night, four rockets and five mortars had been fired from Gaza into Israel during the previous 24 hours. One rocket fired on Thursday evening set off the early warning system in Ashkelon. Defense officials say the rocket landed on the outskirts of the city. Another rocket fell in the vicinity of the Sdot Negev Regional Council. No injuries or damage were reported. In the early hours of Thursday morning, two rockets landed in the vicinity of Sderot. No injuries or damage were reported in those attacks. Earlier, a decision to allow 30 trucks carrying a small amount of fuel and humanitarian goods into Gaza was reversed on Thursday morning, after intelligence warnings of imminent attacks on Gaza border crossings was received, the IDF said. "We received many warnings of attacks on the crossings," the defense official said, adding that fear for the welfare of foreign journalists and diplomats led Israel to refuse them entry into Gaza. The official stressed that this was not the first time that foreigners were barred from entering Gaza. But this past week's closure marks the longest such period during which they have not been able to enter. On Thursday, a group of 20 European diplomats on a trip organized through the French consulate in Jerusalem were turned away at the Erez Crossing. Their Gaza trip had initially been scheduled for last week but it was canceled by the Defense Ministry for security reasons, said Maj. Peter Lerner, spokesman for the coordinator of government activities in the territories. It was rescheduled for Thursday, but then canceled by the ministry again. The group was notified of the decision but arrived at the Erez Crossing anyway, Lerner said. On Thursday, as has been true for the past week, he said, the only people who were allowed to cross were those involved in humanitarian missions, including members of international nongovernmental bodies and the United Nations. "A field trip for diplomats does not fall under that category," he said. Also Thursday, the IDF took the unusual step of delaying the ceremony at which the commander of the IDF's Gaza Division, Brig.-Gen. Moshe Tamir, was to be replaced by Brig.-Gen. Eyal Izenberg. The decision was made because of the tension in the area, and was taken by OC Southern Command Maj.-Gen. Yoav Galant, with the support of Chief of General Staff Lt.-Gen. Gabi Ashkenazi. The changeover ceremony has been rescheduled for next week, barring any further escalation. AP contributed to this report.