According to a statement from the Palestinian Authority, yesterday's Israeli assassination of Mr Abu Ali Mustafa, leader of the Popular Front for the Liberation of Palestine, "sets the stage for comprehensive, unlimited war" in the Middle East. It could plunge "the whole region into a cycle of blood".
Such grave warnings go well beyond the usual political rhetoric in this conflict. They match similar belligerent statements on the Israeli side after a sharp escalation of attacks and counter-attacks over the weekend. They must be taken much more seriously by the international community, so that immediate action can be taken to reduce the growing tension.
This assassination is the boldest action taken so far in the Israeli campaign against selected Palestinian leaders, justified as pre-emptive self-defence against their attacks on Israeli targets. But it brings that strategy into a different league of dangerous provocation. Mr Abu Ali has a much higher profile than other such victims, as a founder member of the Palestine Liberation Organisation, albeit a critic of the Oslo peace process and leader of an organisation formally committed to military resistance against Israel - although without much of a concrete record in that respect.
The political and popular reaction to his death yesterday confirms it is much more likely to forge a unity in adversity between the different Palestinian factions than deter their leaders from the Intifada. It will be more difficult for any movement to be made in next week's planned talks between the Israeli foreign minister, Mr Shimon Peres, and Mr Yasser Arafat, under German sponsorship. It seems as if General Ariel Sharon, the prime minister, wants to prevent political progress exposing profound disagreements in his national coalition cabinet, by this ferocious military retaliation for the deaths of seven Israeli troops and civilians over the weekend.
The Bush administration has been justly criticised for its approach to the mounting violence. Its unwillingness to become involved has facilitated escalation, reinforced by Mr Bush's belief that Mr Arafat is primarily to blame. The United States has a special responsibility in the region because of its power, influence and interests and its experience of handling Israel. There is clear tension between the diplomatic and executive sides of US policy.
This has made more difficult efforts to get the United Nations Security Council involved. But a policy to scale down the tension is available through the Mitchell report (which recommended a phased return to negotiations), the use of international monitors and a joint effort by Israeli and Palestinian leaderships to reduce the violence. It will take a really determined effort by regional and international leaders, alarmed by the drift to war, to put that policy into place.