(Adds details of speech, background) By Khaled Yacoub Oweis DAMASCUS, Nov 8 (Reuters) - Hamas leader Khaled Meshaal on Wednesday vowed retaliation for Israel's artillery strike in Gaza, which Palestinian officials said killed 18 civilians. "Our condemnation will not be in words but in deeds, the resistance will respond," Meshaal told a news conference in Damascus. "All Palestinian groups are urged to activate resistance despite the difficult situation on the ground. Our confidence in our military wing to respond is big," said Meshaal, the group's leader in exile. "The period of calm ended at the end of 2005... The resistance is free to act but the situation on the ground dictates the military performance," he added. Palestinian militant groups including Hamas agreed on a truce to halt attacks against Israeli targets in March 2005. The truce expired at the end of last year but Hamas has largely abided by it until now. The Gaza attack, which drew condemnation across Europe and the Middle East, killed 13 members of one family and was the deadliest strike in the territory in four years. The Palestinian Islamic Jihad group also vowed to carry out suicide bombings. Meshaal did not say what sort of armed response he envisaged. Hamas fighters regularly fire rockets at Israel and the group has carried out suicide bombings inside the Jewish state in the past. The 50-year old leader, whom Israel tried to kill in the 1990s, urged Palestinians to be "careful in the words they use" to condemn the Israeli attack so as not to give the Jewish state what he described as an excuse to kill more Palestinians. He said the international community had encouraged Israel to commit crimes by being lax on the Jewish state. "This massacre sadly comes under the cover that international silence and Arab impotence provide to Israel. The Israelis would not have been able to amplify their crimes otherwise," he said.
