The Israel Air Force attacked 15 Hamas targets in the Gaza Strip overnight Sunday following mortar fire against southern Israeli communities on Saturday evening, the IDF Spokesperson’s Unit announced.The military said the strikes were a response to the earlier rocket fire as well as “terror incidents led and made possible by the Hamas terror organization over the course of the weekend” which included the throwing of grenades, improvised explosive devices, attempts to infiltrate into Israel by damaging the security fence and the burning of Israeli fields by incendiary kites.The mortar fire was the first violation of a fragile ceasefire and two days of relative quiet in southern Israel after the most significant escalation between the IDF and terror groups in the Hamas-run coastal enclave in four years.The first round of sirens was activated Saturday in several nearby communities in the Eshkol Regional Council around 8PM with one mortar falling in open territory and the other intercepted by the Iron Dome missile defense system. Additional sirens sounded in the same communities as well as in the communities Sha'ar Hanegev and Hof Asheklon regions and the city of Sderot several times following additional rocket fire from the Hamas-run Gaza Strip.According to the military the IAF bombed targets across the entire Gaza Strip in three Hamas compounds including two weapon production and storage sites as well as targets belonging to Hamas’s naval force.If Hamas "chooses to follow a path of terrorism and not solve the difficulties of the people of Gaza it will continue to pay a heavy price that will only become steeper, as much as needed," read the statement released by the IDF.The Palestinian news agency Wafa reported that residential homes were damaged when Israeli jets targeted one site in the al-Waha area northwest of Gaza City with three missiles. The Hamas-affiliated Shehab news agency reported that Israeli jets struck targets in Gaza City’s Shejaiya neighborhood as well as in the Nuseirat refugee camp near Deir al-Bireh. Another target was struck outside the southern Gazan city of Rafiah.Earlier in the evening Israeli jets bombed locations in the al-Zaytoun neighborhood in Gaza City as well as targets in Khan Younis and Rafiah.While no group took responsibility for the mortar fire sources in the Gaza Strip said it is believed that the Popular Resistance Committees reportedly carried out the Saturday evening attacks in retaliation for the death of 21-year-old paramedic Razan al-Najar, killed Friday during violent protests in southern Gaza. Meanwhile the IDF announced Sunday morning that a large scale exercise across the southern part of the country would begin despite the heightened tensions in the area. Residents of southern Israel should expect to see an increased presence of troops as well as military equipment and aircraft in the skies over southern Israel. The drill, which will last throughout Wednesday, was planned in advance “to preserve the fitness and preparedness of the troops,” the military said.The Israel Air Force will also be holding a separate drill throughout the country and is set to last until Thursday.