Despite the urge to respond harshly to rocket attacks from the Gaza Strip, Israel should bide its time and wait for the right opportunity to strike Hamas, Defense Minister Ehud Barak said Thursday, a day after a Grad type rocket wounded more than a dozen people in an Ashkelon mall. Barak, who spoke at the closing session of the "Facing Tomorrow" Presidential Conference, said that the "situation in Gaza is quite complicated. My gut reaction is to respond, but when the blood boils it is important to carefully weigh one's options." He added that "we will reinstate quiet and security in Sderot and the Gaza periphery; we'll get results - not mere words - at the right time." "What is demanded of us now is resolve, a deep breath, nerves of steel and cruel tolerance until the proper time," he said. "As a government we have the utmost political and moral responsibility to do everything possible and open every door in order to find the opportunity to make peace. On the other hand, our neighbors must arrive at the understanding that Israel cannot be defeated with terrorism." Earlier Thursday, Barak promised Ashkelon residents that Israel would not suffer continued attacks without a response. "You guys need to bite your lips, but not for [long]," Barak said during a tour of the scene of the attack. "This incident is not simple, and proves that despite the hits that the Palestinians are sustaining in Gaza, they are still shooting," he said, adding that "if the rocket had hit a roof of a house, I would've been going to a funeral." Fifteen people were wounded, including four seriously, by a Grad-model Katyusha rocket that hit a shopping center in Ashkelon just hours after US President George W. Bush arrived to celebrate the state's 60th anniversary. The rocket, fired from Beit Lahiya in northern Gaza, struck the Hutzot Mall in southern Ashkelon, causing considerable damage. Several people were initially trapped under the rubble. The four people in serious condition included a 24-year-old woman and her young daughter. In addition, 87 people were treated for shock. In response, the IDF launched an air strike against a Hamas observation post in the Saja'iya neighborhood in Gaza City. According to Palestinian sources, two operatives were killed in the strike. Palestinians also claimed that the IDF fired artillery shells from north of the Strip. No casualties were reported in this alleged separate strike. Late Wednesday night, two mortar shells fired by Palestinians in the Gaza Strip landed in open areas south of Ashkelon. No casualties or damage were reported.