DAMASCUS, Syria — Secretary of State Colin L. Powell traveled to Damascus and Beirut on Monday for talks aimed at averting a wider Middle East war, and the United States explored the possibility of holding a conference to forge a final peace among Israelis, Palestinians and moderate Arabs.
Powell, on a high-stakes mission to defuse 18 days of heightened hostilities since an Israeli offensive began in the West Bank, appeared to run into initial setbacks on both fronts.
In a move welcomed by the Bush administration, however, Israeli Prime Minister Ariel Sharon said he plans to pull troops and tanks out of the West Bank cities of Jenin and Nablus in a week or less.
Sharon told President Bush about his plans when the American leader called him from Cedar Rapids, Iowa, before a Republican fund-raiser. Bush regarded Israel's move as positive, White House Press Secretary Ari Fleischer said.
"You're starting to see the results of the secretary's hard work," he added.
But Sharon said in an interview with CNN that Israel plans to remain in the West Bank around the headquarters of Palestinian Authority President Yasser Arafat in Ramallah and at the Church of the Nativity in Bethlehem until standoffs over wanted gunmen have been resolved.
In Ramallah on Monday, Israel arrested Marwan Barghouti, the leader of Arafat's Fatah faction and the man Israel holds responsible for dozens of attacks. Sharon said Barghouti will be put on trial.
Meanwhile, witnesses in Tulkarm said Israeli tanks swept in from several directions early today in what an Israeli military source described as "a limited operation to arrest Palestinian militants," the Reuters news agency reported.
A delay in full withdrawal of Israeli forces could complicate Powell's mission, since the U.S. is still searching for the key to breaking the deadlock. As the secretary is finding at every stop, each issue he addresses comes back to the Israeli-Palestinian conflict.
Powell spent most of the day Monday calling on the leaders of Syria and Lebanon to rein in Hezbollah and Palestinian extremists who have launched almost daily attacks across the Lebanese border into Israel and the Golan Heights, which was captured by Israel from Syria. The attacks have coincided with the Israeli army's current operations against the Palestinians in the West Bank.
Israel has threatened a serious military response if the attacks do not subside.
"There is a very real danger of the situation along the border widening the conflict in the region," Powell said in Beirut after talks with Lebanese President Emile Lahoud. "It is essential for all those committed to peace to act immediately to stop actions across the border."
The United States asked Lebanon to increase military deployment in southern areas. "If they could have an increased presence in the south, that might serve as a deterring effect and give them more indications and knowledge about what's going on in south Lebanon," Powell told reporters.
The secretary then called on Syria, which along with Iran has significant influence over Hezbollah, to restrain the militia.
Powell said he had "reasonable assurances" that Lebanon and Syria recognize the potential repercussions from the attacks. And he noted that Lebanon had arrested 24 Palestinians linked to attacks on civilian areas in northern Israel.
"Both said that they would do what they could do to restrain activity of that type," Powell said. However, the secretary also faces strong public opinion, long-standing government policies in the region and a well-entrenched militia. At a news conference in Beirut, he acknowledged that he faced "strong criticism."
Lebanese Foreign Minister Mahmud Hammud charged that Israel is responsible for the escalation in violence because it "blocked all efforts seeking peace and rejected international resolutions that demand its withdrawal from all occupied Arab territories."
Lebanon also has a border dispute with Israel regarding the Golan's Shabaa Farms, against which many of the Hezbollah attacks have been launched. Lebanon considers Hezbollah's attacks the final resistance to Israeli occupation.
Hezbollah pledged to continue its campaign.
"The American administration tries . . . to give the image of a mediator in search of political solutions, when everyone knows it is a partner in all the crimes and massacres that the Zionist enemy is carrying out against the Palestinian people," it said in a statement.
Thousands of Hezbollah supporters protested in the streets of Beirut. As Powell's armored convoy sped through the Lebanese capital, demonstrators who were held out of sight by police chanted, "We loathe America. Powell, get out of here. The Palestinian people are being exterminated by an American decision. America is the leader of terrorism in the world."
Syria's official news agency issued a statement blaming Israel for the violence and saying it would be better to "eradicate the causes rather than waste time condemning" attacks.