If, as seems all but certain, Osama bin Laden master-minded the atrocity of New York, it was, self-evidently, directed against the US, in line with his call on all Muslims to "kill Americans and loot their riches wherever you find them".
But, indirectly, the target was Muslim too, in the shape of Arab regimes, and not least the House of Saud, which claims to be the most quintessentially Muslim of all. On returning home after their victory over the Russians, the "Arab Afghans" had at first concentrated on an "internal" jihad against these "apostate" rulers who they deemed Muslim in name only.
It was only in the later 1990s that they resumed the external one, with the US, their former ally, replacing the Soviet Union as the mortal foe: hence the bombing of US embassies in Nairobi and Dar al-Salaam in 1998. They deemed it more profitable, partly because it chimed with a steadily mounting anti-Americanism among the Arab peoples. But with this switch in priorities, they certainly did not forget the enemies within. Their sin, in Saudi Arabia's case, was to have turned the lands of Mecca and Madin a into an American "colony", or, in the case of all of them, to do nothing to rescue Jerusalem and al-Aqsa from the Zionist usurper.
Of all the grounds on which bin Laden could hope to embarrass Arab regimes the most fertile is Palestine - Palestine and their reliance on a congenitally pro-Israeli US to extricate themselves from the shame and ignominy, the threat to their existences, which this chief of Arab causes has become.
Confined to Israelis and Palestinians alone, the intifada would be a hopelessly unequal struggle. But helping to sustain the Palestinians has been the knowledge that if the Arab world could ever be induced to deploy a mere portion of its enormous potentialities on their behalf, it could have wrought a dramatic shift of the balance of power in their favour.
But never has the Arab world seemed more scandalously absent, and never, as the intifada approaches its first anniversary this week, have Arab commentators been more outspoken in saying so. They relentlessly assail the "shameful impotence" and "helpless defeatism" of Arab regimes, especially Egypt and Jordan.
The impotence is seen to have deep roots, amounting, in many people's view, to the bankruptcy of the whole peace-seeking strategy that has been unfolding since the Egyptian-Israeli treaty of 1978. It was then that the Arabs first turned so earnestly to the US, erecting it into the honest broker who would compensate them diplomatically for what they could not do militarily.
The Palestinians' anger and disappointment is shared by the Arab "street". True, after an initial effervescence, this street has been relatively quiescent. Yet it seems as emotionally embroiled in Palestine as ever. According to a recent survey, some 60 per cent of the people of Saudi Arabia, Kuwait, the Emirates and Lebanon regard Palestine as the "single most important issue to them personally"; in Egypt, the key country, that figure rises to a remarkable 79 per cent.
"The Palestinian issue remains an identity concern for most Arabs," commented Shibley Telhami, an Egyptian academic. "Most Arabs are shamed by their inability to help the Palestinians."
The economic reforms on which President Mubarak has staked his regime's future are in deepening trouble. "People see in the Palestinian question a vehicle for protesting their own social and political predicaments," said Egypti. Last month, as one body of security forces kept a nervous eye on worshippers brandishing Korans and banners proclaiming that "al-Aqsa is captive", another clashed with thousands of graduates clamouring for their quota of government-guaranteed jobs - convergent symptoms of a latent discontent which could explode into full-scale confrontation at any time.
But the greatest blow to the regimes has come from the US, now betraying, as never before, the trust which the late President Sadat first placed in it. At a time when, with the rise of General Sharon and the most belligerent government in Israel's history, the US simply walked away from the peace process - and then blamed Arafat, not Sharon, for its collapse.
"There is complete and blatant American bias in Israel's favour," said an unusually forthright Mubarak last month. And his confidant, Ibrahim Nafi, editor of al-Ahram, warned that throughout the Arab world "hatred of America has reached unprecedented levels." Another government newspaper, al-Akhbar, said the Arab-Israeli conflict was being superseded by "a broader and more dangerous Arab-American conflict".
Little did al-Akhbar foresee just how. The most spectacular terrorist exploit of all time was something else as well: the most striking possible demonstration of the leverage which the Arab regimes, had they chosen, could have brought to bear on behalf of Palestine. In its colossal impact on the world economy, New York amounts to the terrorists' version of the oil weapon which the Arabs last unsheathed in 1973, during the last full-scale Arab-Israeli war, but which, in their deference to America, they have more or less promised never to unsheath again.
Will the regimes now seek to profit from this terrible event to impress on the US the absolute need to achieve a lasting Israeli-Palestinian settlement, for the world's sake as well as their own? Or will they, in heeding America's demand to join the coalition against terror, end up more subservient to it than ever, at Palestine's expense? The ceasefire to which Israelis and Palestinians have committed themselves in the wake of the atrocity is seen as a step in the right direction; a necessary US re-engagement in the conflict from which Ariel Sharon did not emerge as victor.
But it is a small step only, and the fear is that it is a replay of the Gulf war. It will, in effect, make the Americans more pro-Israeli than ever. They will have little time for basic Arab arguments about the root causes of terrorism.
But these apprehensions have not stopped Arab regimes from rushing to identify themselves with the anti-terror campaign. After all, some of them, Egypt and Saudi Arabia, were themselves targets of the "Arab Afghans" internal jihad. And the Arab and Muslim public has shown some revulsion at what the terrorists have done in their name.
Doubtless, it is less whole-hearted than elsewhere; an opinion poll in Lebanon, for example, found that 16.7 per cent were "pleased" by it. But some newspapers have been quite radical in their condemnation. Kuwait's al-Watan said it was not just the Americans who "must transform themselves, so must the Arab world and the Islamic mind," and rid itself of the widespread approval of violence, martyrdom and jihad that pervades the "dominant religious culture ".
But America's categoric "you are with us or against us", is ominous for the regimes. Mubarak and others have made it clear that a Western onslaught on Afghanistan will be bad enough, but after earlier attacks on Iraq, Libya and Sudan, it will fuel the perception of Western hatred and hostility to all things Arab or Muslim.
Clerics and religious scholars, such as those in pro-Western Jordan, have decreed that joining any US-led "aggression" against "any Muslim country" is "religiously forbidden, treason to God, his prophet and the faithful".
But worse, for the Arabs, is the prospect that the Americans, having dealt with Afghanistan, will turn to terrorists closer to home. The first likely target is Iraq. Arab regimes which, under pressure of public opinion, were so hostile to recent Anglo-American attempts to tighten the embargo on Saddam Hussein would find it even more difficult to support a renewed military campaign against him.
But there is yet worse than that. According to Arab press reports, the US Under-Secretary of State, William Burns, delivered to six Arab ambassadors what amounted to an ultimatum: co-operate fully or face the full wrath of the West. Co-operation required the arrest or extradition of all terrorists in all Arab countries.
Who exactly are these terrorists? Evidently, to the US, they include Lebanon's Hizbullah. The Lebanese government has been shocked to learn that the US expects it to accomplish the almost impossible task of dismantling an organisation that not only enjoys great prestige for its resistance to Israel, but has become an integral part of the country's fabric. And they almost certainly include the Palestinian Hamas and Islamic Jihad.
These are symbols and instruments of what Arabs regard as legitimate resistance to Israel. In moving against them the regimes would be grievously flouting public sentiment already roused on the Palestinians' behalf.
They know it. Mubarak has called for a UN conference that would define the differences between legitimate and illegitimate political violence. Saudi Arabia, that other key US ally, is in a particularly tough spot. Upholder of a deeply conservative religious orthodoxy from which bin Laden springs, deeply sensitive to the Palestinian issue, it has on the one hand put advertisements in US newspapers saying "America, We Stand With You", while, on the other, an official asserts: "We will not agree under any circumstances on hitting any sister country like Syria, or groups resisting occupation like Hamas, Islamic Jihad and Hizbullah."
From what is known of Arab Afghan doctrines and theories of action, bin Laden is clearly a believer of sorts in the "clash of civilisations", in an implacable enmity between Islam and the infidel West, and with his New York tour de force he undoubtedly sought to bring this Manichean conflict to a decisive climax.
His calculation is that when the West counter-attacks, the Muslims will rise up in a general intifada that will not only defeat it, but bring down those "apostate", pseudo-Muslim regimes that do its bidding.
But the wider and fiercer America's war on terror and the more retreat or humiliation it requires of Arab regimes at Palestine's expense, the less improbable it becomes that, in the coming tumult, something, at least, of his messianic ambition will be fulfilled.