Israel says its airstrikes are aimed at militants, and it blames Hamas for the damage, accusing the group of using residential areas for cover.Reconstruction since the 2008-9 fighting has been slow, in large part because of Israel's blockade. Israel imposed the restrictions in 2007, after Hamas, a militant group sworn to its destruction, wrested power over the coastal strip from the government of Western-backed Palestinian President Mahmoud Abbas. Under international pressure, Israel loosened the blockade in 2010 but maintained tight restrictions on imports of glass, cement, metal and other construction materials, saying they could be diverted for military use. Only U.N agencies and international organizations in the Palestinian territory are allowed to import such material from Israel for their own projects. To make up the shortage, a bustling smuggling industry through underground tunnels along the Egyptian border has sprung up. While prices for key construction goods have come down, they still remain expensive for the majority of the population in Gaza, where the unemployment rate is over 30 percent and 80 percent of the people rely on U.N. handouts. "The blockade in terms of housing impacts us primarily â¿¿ the U.N. â¿¿and the people who are most vulnerable who don't have access to jobs or economic opportunity," said Scott Anderson, deputy director of the U.N. Relief and Works Agency. "People who have money, it is easily available." In the short term, there is no relief in sight. During the recent offensive, Israel heavily targeted the tunnels, which are also used to bring weapons into Gaza. Residents along the border say that smugglers and tunnel owners are still inspecting the damage but that many of the tunnels still operate, though at reduced capacity. An Egyptian security official, speaking on condition of anonymity because he was not authorized to talk to the media, estimated that half the tunnels are not functioning.