During the weekend, some senior administration officials suggested that it was more likely that the weapons were destined for the anti-Israeli Lebanese group Hezbollah.

But there is no hard evidence that Iran has ever shipped weapons either to the Palestinian Authority or to either of the anti-Israeli Palestinian groups.

The third Palestinian who was killed was said to be a member of Islamic Jihad, a hard-line anti-Israeli group.

The Joint Chiefs of Staff have argued against diluting the military mission by defining the two anti-Israeli groups as immediate targets, Pentagon officials said.

The weapons pass through Syria, which also provides safe haven to a number of anti-Israeli groups.

But he was also a longtime member of Hamas, the virulently anti-Israeli Islamic group.

The only claim of responsibility for the bombing came from a caller who said he represented an anti-American, anti-Israeli group called Muslims Against Global Oppression.

They suggested that the arms might have been headed for Hezbollah, the anti-Israeli Lebanese Shiite group.

American aides officially regard Iran, which has long backed anti-Israeli militant groups like Hezbollah, as one of the world's leading state sponsors of terrorism.

But support for anti-Israeli groups, especially Hamas, is far more open and widespread than that for Mr. bin Laden.