Israel, Gaza Launch Heaviest Strikes Since Nov. Truce No reported casualties By Newser Editors and Wire Services Posted Apr 3, 2013 9:54 AM CDT 66 comments Comments Israeli Border Police take position during clashes in Jerusalem's Old City, Tuesday, April 2, 2013. (Bernat Armangue) (Newser) – Palestinian militants launched several rockets into southern Israel, as Israeli aircraft struck targets in the Gaza Strip early today in the heaviest exchange of fire between the sides since they agreed to an internationally brokered ceasefire in November. There were no casualties reported, but the violence threatened to shatter the calm that has prevailed for more than four months and prompted Israel's new defense minister to warn that the Jewish state will not sit back if militants attack the south of the country. Although there was no claim of responsibility for the rockets, defense minister Moshe Yaalon said he holds Hamas responsible for all such attacks from the seaside strip. In recent weeks, there have been a handful of rocket attacks; overnight, Israel responded for the first time by striking a pair of empty fields in northern and eastern Gaza. Around the time Yaalon was speaking this morning, two more rockets exploded in the Israeli border town of Sderot, according to police, prompting air raid sirens. The Israeli military said a total of five rockets had been fired in the past 24 hours, including two that exploded prematurely inside Gaza.