Armed assailants in black masks burned and vandalized a UN summer camp site Sunday and left behind three bullets next to written death threats against UN officials - the latest escalation of tensions between Islamic extremists and UN representatives in Hamas-ruled Gaza. Also Sunday, a UN agency reported that three-quarters of the damage inflicted on Gaza by Israel's war against Hamas more than a year ago has not been repaired or rebuilt. The report warned that the international community is being increasingly sidelined in Gaza because of Israel's blockade of the territory. There was no immediate claim of responsibility for the attack on the UN camp site on the Gaza shore, near Gaza City. However, extremists, including Hamas hardliners, have repeatedly railed against the UN as being a bridgehead for the West and corrupting Gaza's youth by teaching “unIslamic” subjects in schools and summer camps.