WASHINGTON - A powerful remote-controlled bomb blew up under an official U.S. convoy in the Gaza Strip yesterday, killing three American security guards and drawing the United States more deeply into the Israeli-Palestinian conflict.
The explosion marked the first fatal attack on U.S. personnel in the 3-year-old Palestinian uprising. A State Department spokesman said the Bush administration assumed that the American convoy had been specifically targeted.
President Bush quickly blamed Palestinian authorities, particularly Yasser Arafat, for a failure to crack down on militant groups - a failure the president called the "greatest obstacle" to achieving statehood.
"Palestinian authorities should have acted long ago to fight terror in all its forms," Bush said in a statement. "There must be an empowered prime minister who controls all Palestinian security forces, reforms that continue to be blocked by Yasser Arafat."
The attack served to push the administration even further away from an active push to renew peace talks.
"There's not going to be any progress until they destroy these terrorist groups," said a senior administration official who spoke on condition of anonymity.
At a minimum, the official said, the attack is likely to diminish American forays into the occupied territories to speak with Palestinians about political, economic or cultural matters.
Under the U.S.-backed "road map" plan that's intended to lead eventually to an independent Palestinian state, Palestinian leaders are required to break up militant groups that target Israelis.
The attack on the three-car convoy broke with a pattern among Palestinian militant groups of confining their attacks to Israeli civilian and military targets. None of the known Palestinian militant groups - Hamas, Islamic Jihad and al Aqsa Martyrs Brigade - claimed responsibility, as they frequently do after attacks on Israelis and, in fact, distanced themselves from it.
Interviewed on the Arab television station al-Jazeera, a Hamas representative in Beirut, Usamah Hamdan, said his group targets only "the occupier," referring to Israel, and said, "The resistance has a clear policy, which has not changed."
The possibility that Palestinian extremists are broadening their targets beyond Israelis points to a growing threat to Americans throughout the Middle East. Early this year, a U.S. diplomat was killed in Jordan. In Iraq, U.S. occupation troops are coming under deadly assault almost daily. Yesterday, the United States advised the few hundred Americans who live or work in Gaza to leave.
Richard A. Boucher, the State Department spokesman, said "one has to start with the assumption" that the perpetrators were familiar with the Gaza Strip and had operated there in the past.
The FBI and the State Department's Bureau of Diplomatic Security will investigate the attack with Palestinian and Israeli authorities, officials said.
Arafat condemned the attack as an "awful crime," and his recently appointed prime minister, Ahmed Qureia, promised to track down those responsible. Officials gave no indication of what action the United States might take once the perpetrators are discovered, other than to say they would be brought to justice.
The three-vehicle convoy was carrying officials of the American Embassy in Tel Aviv into Gaza to interview Palestinians who are seeking Fulbright scholarships to study or teach in the United States.
"The Americans who were attacked today were pursuing a vision for a better future for the Palestinian people," Bush said. "This is another example of how the terrorists are enemies of progress and opportunity for the Palestinian people."
The attack occurred a few miles from the Erez checkpoint separating Israel from the Gaza Strip. Embassy officials and security officers occupied two of the vehicles. The third carried Palestinian security personnel, who usually accompany American officials into Gaza.
The dead Americans, all employed by DynCorp, a security company based in Virginia, were John Branchizio, 37, of Texas; Mark T. Parson, 31, of New York; and John Martin Linde Jr., 30, of Missouri. A fourth American was wounded.
Daniel C. Kurtzer, the American ambassador to Israel, noted that while yesterday's attack was the first in which U.S. personnel were killed or seriously wounded, an embassy vehicle was attacked in Gaza in June.
Matthew Levitt, a terrorism specialist at the Washington Institute for Near East Policy, said the explosive used yesterday appeared to be "an extremely sophisticated roadside bomb."
Roadside bombs have previously been used to attack Israeli tanks in the Gaza Strip. They were frequently used by Hezbollah guerrillas against the Israeli military in southern Lebanon.