JERUSALEM, Dec. 11 (JTA) — In the half-month since he arrived in the Middle East to broker an Israeli-Palestinian cease-fire, U.S. envoy Anthony Zinni has learned the bitter taste of failure. Since his arrival on Nov. 26, the square-jawed former Marine Corps general has managed to bring the two sides together for a series of security talks. But those talks were so acrimonious that earlier this week Zinni reportedly threatened to leave the region within 48 hours if the Israelis and Palestinians did not get serious about the quest for peace. U.S. officials later denied that Zinni had made the threat. Just the same, there were no statements from any of the parties indicating that the security talks were bearing fruit. On Tuesday, Israeli soldiers killed two Palestinians who tried to run a roadblock near the West Bank city of Tulkarm. According to an Israel Defense Force investigation into the incident, the men were driving a car without license plates that had been stolen from the home of an IDF officer. In the Gaza Strip, Israeli helicopters fired on a building of the Palestinian Authority´s Force 17 security service in retaliation for a mortar attack on a Jewish settlement that injured two children. Whether by coincidence or not, the violence Zinni sought to defuse has only increased since he came to the region. Within days after his arrival, there was the deadly weekend of suicide bombings in Jerusalem and Haifa that claimed the lives of 26 victims and left hundreds wounded. One of the victims, Ido Cohen, 17, was critically wounded in the Dec. 1 attack on the Ben-Yehuda pedestrian mall in Jerusalem. He died Saturday night at a Jerusalem hospital. Cohen, who was in a coma with severe head wounds, never regained consciousness. Nor did the terror attacks end with the Dec. 1 and 2 bombings. On Sunday, there was a suicide bombing near Haifa — but this time the only fatality was the bomber himself. In the meantime, Israel has continued its policy of killing suspected terrorists, a move Israeli officials say is the only way to prevent more terror. According to a poll published last Friday in the Israeli daily Yediot Achronot, 74 percent of Israelis back the policy — but only 22 percent believe it prevents more terrorism. This week, the policy resulted in the deaths of two Palestinian boys in Hebron. Israeli officials said the target of Monday´s helicopter attack in the West Bank was a leader of Islamic Jihad, Mohammed Sidr, who was injured in the assault. The helicopter strike came one day after Israel´s Security Cabinet approved more military strikes against Palestinian targets. The leader of Palestinian militias in the West Bank, Marwan Barghouti, described the attack as an "ugly crime" and called on the United States to condemn it. Since the Dec. 1 and 2 terror bombings, however, international condemnation has focused on Palestinian Authority President Yasser Arafat. This week, the European Union joined U.S. officials in taking a tough stance against Arab terrorism. E.U. foreign ministers meeting in Brussels issued a statement Monday that branded Hamas and Islamic Jihad "terrorist networks" and demanded that the Palestinian Authority dismantle them. The ministers also called on the Palestinian Authority to arrest and try terror suspects and issue a "public appeal in Arabic for an end to the armed intifada." The statement was welcomed by Israeli officials, who believe the European Union is generally pro-Palestinian. Meanwhile, the United States has been keeping up the pressure on Arafat. Sunday´s terror attack near Haifa reinforced U.S. doubts regarding Arafat´s ability — and willingness — to rein in terrorists. That attack, which took place at a major intersection just outside Haifa, injured at least 23 Israelis. Local police believe the man intended to carry out the attack on a bus. Following the attack, U.S. Secretary of State Colin Powell questioned Arafat´s ability to lead the Palestinians. Those misgivings were echoed Sunday by Vice President Dick Cheney. The violence by Arab terrorists is "destroying" Arafat´s authority, Powell said Sunday. The terrorists "will not push Israel into the sea. So they will not be successful if that is their goal," he added. Cheney also questioned Arafat´s ability to exercise control. He said on NBC-TV´s "Meet the Press" that "until Arafat demonstrates that he is serious about suicide attackers, there won´t be progress" in efforts to reach an Israeli-Palestinian cease-fire. The Palestinians, he said, "are led by someone who can´t control terrorists." The U.S. pressure prompted Arafat to launch an unusually harsh verbal attack on U.S. officials, accusing them of pro-Israel bias. Arafat became visibly angry last Friday night when an interviewer for Israel´s Channel One television asked him about the continued U.S. pressure on him to clamp down on terrorists. "Dear God, who cares about the Americans," Arafat said. "The Americans are on your side and they give you everything." He went on to accuse the United States of providing the airplanes and tanks Israel uses against the Palestinians. Earlier last Friday, Arafat said Palestinian officials had arrested 17 of 33 terrorists on a list presented by Zinni earlier in the week. Arafat said 15 were arrested in the West Bank city of Jenin, and that more arrests were on the way. Last Friday, Zinni hosted the first of several sessions with Israeli and Palestinian security officials. The discussions, which also were held this week, focused on finding practical steps to combat terror and violence. According to Palestinian officials, the two sides came close to a fistfight at last Friday´s meeting. Given such reports, few observers are optimistic about Zinni´s peace mission. Earlier in the weekend, Israel resumed military strikes in the Gaza Strip. The continued airstrikes have prompted some to question whether Prime Minister Ariel Sharon is out to topple Arafat. For a majority of Israelis, according to a poll, that would be just fine. According to a Gallup poll published last Friday in the Israeli daily Ma´ariv, more than half of the Israelis questioned said they would be happy if Arafat was deposed.