Israel's attack on a Hamas leader could make it harder for the new Palestinian leadership to combat terrorism, President George W. Bush said yesterday. Bush said he was "troubled" by the Israeli helicopter attack on Abdel Aziz Rantisi in Gaza. Such incidents don't promote Israel's security, he said, and may "make it more difficult for the Palestinian leadership to fight off terrorist attacks."

"I regret the loss of innocent life," Bush told reporters in the Oval Office.

"I am determined to keep the process on the road to peace," Bush said. "And I believe with responsible leadership by all parties, we can bring peace to the region - and I emphasize all parties must behave responsibly to achieve that objective."

Earier, National Security Advisor Condoleezza Rice called Prime Minister Ariel Sharon's chief of staff, Doiv Weisglass, demanding Israel explain why it was necessary to try to assassinate the Hamas hardliner.

Israeli intelligence officials and the Prime Minister's Office were trying to prove to the Americans that Rantisi was "not a ticking bomb, but a factory of ticking bombs."

Three people were killed, including a 50-year-old woman, an eight-year-old girl, and a Rantisi bodyguard, when five rockets were fired from helicopters overhead Rantisi's car on a crowded main street in Gaza City, wounding at least 25 people.

Later, three more Palestinians were killed - and more than 30 wounded - when a helicopter rocket hit their truck after they fired Qassam rockets at Sderot.

Palestinian Prime Minister Mahmoud Abbas condemned the Gaza City missile strike, calling the failed attempt a "terrorist attack ... intended to obstruct and sabotage the political process," Abbas's office said. Abbas called on the U.S. to intervene immediately to prevent further Israeli military actions. Sources close to Abbas admitted he was deeply embarrassed by the attempt on Rantisi's life after he had spent so much effort trying to win the confidence of Hamas for a cease-fire plan that would pave the way for the road map.

Palestinian Cabinet Minister Yasser Abed Rabo, considered close to Yasser Arafat, called the attack "an act of terror that bombed the road map, putting a large exclamation point over the real intentions of Sharon."

Rantisi, from his hospital bed at Shafi Hospital in Gaza, called for continuing the "holy war" until there are no more "criminal Zionists" left in the country. "We will continue with our holy war and resistance until every last criminal Zionist is evicted from this land," Rantisi told Al Jazeera. A pediatrician and one of the best-known Hamas spokesmen, Rantisi is the highest-ranking Palestinian militant to be targeted in an Israeli assassination attempt.

Prime Minister Ariel Sharon and Defense Minister Shaul Mofaz authorized the assassination attempt on Sunday after the attack on the Erez Junction army outpost that killed four soldiers, government and security sources said last night. The sources said Rantisi's name has come up on the past as a candidate for assassination, but the politicians did not authorize it.

A few weeks ago, a decision was made to strike at Rantisi as well as other Hamas leaders - including, reportedly, Hamas spiritual patron Sheikh Ahmed Yassin - but the operation against Rantisi was canceled at the last minute for political and operational reasons.

After the attack, Rice and U.S. Ambassador Daniel Kurtzer called the Prime Minister's Office, asking bureau chief Dov Weisglass if Israel had backed down from its commitments made at the Aqaba summit. Israel's ambassador in Washington, Danny Ayalon, spoke with senior White House officials about the operation.

White House sources said the attack on Rantisi was evidence of Israel disregarding U.S. positions made clear at Aqaba. According to White House sources, American officials at Aqaba specifically asked Israeli officials to not to take any actions that could inflame the Palestinian public in the coming weeks to give the Abbas government time to consolidate its hold. Last night, the administration was regarding the attempted assassination as a political act, not a security one, and appeared to be rejecting Israeli explanations. The fact that Bush reiterated earlier statements by his spokesman, after Rice heard from Weisglass, was seen in Washington as evidence that the administration has not accepted the Israeli explanations. Bush didn't call Sharon - but Russian President Vladimir Putin did, to protest the attack.

The Israeli government's message is that Rantisi was not a ticking bomb, but "a factory for ticking bombs," plotting mass terror attacks to destroy the Aqaba process. "He launched terror attacks and it is absurd to put him on the political level. It was obvious the Americans would not like the operation but even Bush called the Hamas enemies of peace yesterday. We told Abu Mazen (Abbas) we will continue to operate against ticking bombs and foil attacks, as long as the Palestinian Authority does nothing to stop them," said a government source.

Another source said: "Under the circumstances, action had to be taken to save the Aqaba process." Israel will present hard intelligence evidence to the Americans proving Rantisi's involvement as an initiator and planner of attacks, the source said. "If only a little of what he planned took place, we would have had dozens of casualties and that would have stopped the process."

A few hours after the IDF rocket attacks, Qassam rockets were fired from Beit Hanoun at Sderot for the first time in two weeks. Anticipating such a reaction to the attack against Rantisi, helicopters remained in the air over the area, and one spotted the truck from which the Qassams were launched, sending rockets into the truck. That killed another three Palestinians who were in the truck, and according to Palestinian sources, wounding some 30 others in the vicinity who were hit by shrapnel.

The Hamas vowed revenge for the failed attempt on its number two man's life, saying vengeance would come "in the near future." Sheikh Yassin said "Israel continues to strike at us without distinguishing between civilians and military people and now every Israeli should know that they are a target." Other spokesmen called for a cessation of the dialogue with Abbas, but so far, no official announcement to that effect has been issued.

Rantisi, 54, is considered the most extreme hardliner in the current Hamas leadership and Israel believes he has stepped into the role of the overall commander of the military wing of the Islamic fundamentalist movement. Often arrested - and then released - by the Palestinian Authority he is considered the number two in the movement after Yassin.

He was the leading spokesman for the movement after the Aqaba summit, rejecting the road map and vowing on Saturday that Hamas would ignore Abbas' calls for a cease-fire.

Nonetheless, after a Abbas press conference on Sunday, he said the organization would examine the Palestinian prime minister's statements and appeared to open the way to the resumption of dialogue toward a cease-fire.

Mahmoud a Zahar, another Hamas spokesman last night said: "Israelis only understand the language of force and we say to them an eye for an eye and a tooth for a tooth, and political negotiation for political negotiations."

The attack broke open the fault line of Israeli politics, with the left lining up against the timing of the attack and the right backing it completely. But there were divisions inside the coalition, with several Shinui MKs slamming the assassination attempt. Ronni Brizon, MK, for example said "whoever decided to conduct this assassination operation meant to assassinate the road map together with Rantisi. Not only did the operation fail, but it was a bad and dangerous decision."

The hardliner

Some Palestinians were predicting that the failed attempt on Rantisi will propel him into the slot of the most popular Palestinian politician, ahead of Arafat. Already, a poll by the Jerusalem Center for Communications and Media taken before the Aqaba poll showed Hamas had taken over first place from Fatah for the first time as the most popular political movement among Palestinians.

Together with Imad Alali, who represents the movement in Syria, Rantisi took the hard line in Hamas, rejecting any cease-fire under any condition and rejecting any attempts to turn the Hamas into a political party that takes part in coming Palestinian elections.

But in recent weeks, particularly after the Iraq war, with American pressure on Hamas-supporting states in the region, the hardline wing in the movement had been weakened. Indeed, the Hamas leadership, including Yassin, imposed on Rantisi and other extremists the dialogue with the PA leadership.

Ever since Israel accepted the road map and Abbas announced - and reiterated repeatedly - his intentions to conduct a dialogue with Hamas, the leadership has been repositioning itself as ready to consider an end to the terror attacks, if it gets a piece of the government, and guarantees its people would not be harmed. There were even indications it was considering running a slate of candidates in the Palestinian elections called for in the road map.

Over the last week, the Hamas went from being vehemently opposed to the Abbas speech in Aqaba, to being mollified by his press conference in Ramallah. It went so far as to follow up the press conference with an announcement that it was ready to resume dialogue with Abbas.

But a Rantisi assassination, whether successful or not, will strengthen the extremist wing of the Hamas, which will now regard itself free of any understandings with the Abbas government that in the last two weeks, say the Palestinians, put an end to the Qassam rocket attacks on Sderot from Gaza, and attacks against Israeli targets inside the Green Line.