Late Monday, Israel's UN envoy filed a letter of complaint about the continued rocket attacks from Gaza to the Secretary-General and the president of the Security Council, whose rotating chair is currently held by Libya. Ambassador Gabriela Shalev warned that the Hamas attacks would hinder efforts to reach a "stable and durable cease-fire" - a deliberate echo of language adopted by the Security Council in its January resolution calling for an end to Israel's Operation Cast Lead offensive in Gaza. "These ongoing attacks not only hinder efforts to reach a stable and durable cease-fire, but they represent an ongoing threat to the peace and security of Israel, as well as the people of Gaza," she wrote. She specifically noted attacks on the South on Sunday, when a Kassam hit a school in Sderot, as well as a Grad attack on Asheklon on Saturday, in which two civilians were wounded. "Had the school building not been closed for the Jewish Sabbath, there likely would have been many more casualties. As a result of this attack and the ongoing security threat, schools are closed and classes are suspended across Ashkelon which constitutes a humanitarian problem," she noted. She reiterated Israeli's right to self-defense, citing the often-quoted Article 51 in the UN Charter, and said that Israel would "continue to safeguard the security of its citizens and will ensure that the situation in southern Israel does not return to the status quo ante of December 2008 [before Operation Cast Lead]." "Israel will not tolerate, and will respond accordingly to attacks against its citizens," she concluded.