Hamas and Islamic Jihad declared an end to their seven-week intifada ceasefire yesterday and vowed bloody revenge against the people of Israel, after Israeli helicopters killed one of the most senior Hamas leaders in a missile strike on his car in Gaza City.
Recognising that the Israeli-Palestinian conflict is again spiralling into heavy violence following the Hamas bus bombing in Jerusalem on Tuesday in which 20 people were killed, the US Secretary of State, Mr Colin Powell, issued a desperate plea to Palestinian Authority President Yasser Arafat to use his influence to "end terror" - to arrest bombers and bomb-makers, and confiscate their weaponry.
Only such action, he said, could prevent the collapse of the "road map" diplomatic process, which is intended to assure the Palestinians of statehood by 2005. Terrorism must not be allowed to triumph, Mr Powell went on. "Those who are determined to blow up the road map must not be allowed to succeed."
But the signs last night were that Israel's killing of Mr Ismail Abu Shanab - the third most senior figure in Hamas - yesterday would reduce the likelihood of any such intervention. Hours before the Israeli helicopter strike, in which two of Mr Shanab's bodyguards were also killed, Mr Arafat had given lukewarm support for a plan, drawn up by the Palestinian Security Minister, Mr Mohammad Dahlan, and energetically backed by the Prime Minister, Mr Mahmoud Abbas, to arrest senior Hamas figures and take other measures to prevent further suicide bombings. But following the Gaza strike, which Mr Abbas denounced as "a despicable action" by Israel, he said it would be harder to mount such a crackdown.
Indeed, Hamas supporters, thousands of whom gathered at Mr Shanab's home last night to demand vengeance, warned Mr Abbas, and any other Palestinian leaders who were contemplating confronting them, that they would be better advised to flee Palestinian territory. Some demanded the resignation of Mr Abbas resign.
The Palestinian prime minister now finds himself threatened by Hamas not to act against it, criticised relentlessly by the far more popular Mr Arafat and pressured by Israel and the US to dismantle the extremist groups. Mr John Wolf, the US official supposed to be supervising implementation of the road map, reportedly told Mr Abbas earlier yesterday that if he did not take action, he would "lose the support of President Bush".
The helicopter strike - five missiles hit Mr Shanab's station-wagon as he drove to his home from a local university, and reduced it to a smoking twisted metal skeleton - put an end to several weeks in which, as the ceasefire has limped along, Israel had refrained from targeting alleged intifada kingpins. After approving a series of military moves in response to the Tuesday suicide bombing, the government of Mr Ariel Sharon had declared: "If the Palestinian government does not take all necessary steps in the war on terror - real and substantive steps - it will not be possible to move to the stage of diplomatic talks." Israeli troops also entered several West Bank cities yesterday, arresting a Hamas activist carrying explosives and uncovering what they said was a weapons factory in Nablus. A Palestinian teenager was killed in Tulkarm as Israeli troops tried, and failed, to arrest two fleeing Fatah activists.
Mr Shanab, who was in his 50s, played a central role in negotiating the hudna - the intra-Palestinian ceasefire declared by most factions at the end of June. Although plainly subscribing to Hamas's ideological commitment to the destruction of Israel, he was perceived to be a relative moderate. In his last interview, with an Israeli TV station on Wednesday, he said he was "not scared of threats" from Israel. Despite Tuesday's bombing, he asserted that Hamas was abiding by the ceasefire and said: "If the Israelis want peace, we've given them the hudna." Israeli officials rejected suggestions that Mr Shanab was a political leader.
Other Hamas leaders have now gone into hiding. Emerging to give separate interviews, the Hamas leader Sheikh Ahmed Yassin and his colleague, Abdel-Aziz Rantisi, blamed the Israeli government for the failure of the intifada truce.
The toll of fatalities from Tuesday's bombing rose to 20 yesterday, five of them US citizens, with the death in hospital of one more victim.