Not long before the Second World War, Stanley Baldwin, who was Britain's Prime Minister, warned that "the bomber will always get through". Today, we can argue that the suicide bomber will always get through. Maybe not all of them. We may never know how many other hijackers failed to board domestic flights in the United States on Tuesday morning, but enough to produce carnage on an awesome, incomprehensive scale. Yet still we have not begun to address this phenomenon. The suicide bomber is here to stay. It is an exclusive weapon that belongs to "them" not us, and no military power appears able to deal with this phenomenon.
Partly because of the suicide bomber, the Israelis fled Lebanon. Specifically because of a suicide bomber, the Americans fled Lebanon 17 years earlier. I still remember Vice-President George Bush, now George Bush Senior, visibly moved amid the ruins of the US Marine base in Beirut, where 241 American servicemen had just been slaughtered. "We are not going to let a bunch of insidious terrorist cowards, shake the foreign policy of the United States," he told us. "Foreign policy is not going to be dictated or changed by terror." A few months later, the Marines upped sticks and ran away from Lebanon, "redeployed" to their ships offshore.
Not long ago, I was chatting to an Indian soldier, a veteran of Delhi's involvement in the Sri Lanka war now serving with the UN in southern Lebanon. How did the Tamil suicide bombers compare those of the Lebanese Hizbollah I asked him? The soldier raised his eyebrows. "The Hizbollah has nothing on those guys," he said. "Just think, they all carry a suicide capsule. I told my soldiers to drive at 100 miles an hour on the roads of Sri Lanka in case one of them hurled himself into the jeep." The Hizbollah may take their inspiration from the martyrdom of the prophet Hussain, and the Palestinian suicide bombers may take theirs from the Hizbollah.
But there is no military answer to this. As long as "our" side will risk but not give its lives (cost-free war, after all, was partly an American invention) the suicide bomber is the other side's nuclear weapon. That desperate, pitiful phone call from the passenger on her way to her doom in the Boeing 767 crash on the Pentagon told her husband that the hijackers held knives and box-cutters. Knives and box-cutters; that's all you need now to inflict a crashing physical defeat on a superpower. That and a plane with a heavy fuel load.
But the suicide bomber does not conform to a set of identical characteristics. Many of the callow Palestinian youths blowing themselves to bits, with, more often than not, the most innocent of Israelis, have little or no formal education. They have poor knowledge of the Koran but a powerful sense of fury, despair and self-righteousness to propel them. The Hizbollah suicide bombers were more deeply versed in the Koran, older, often with years of imprisonment to steel them in the hours before their immolation.
Tuesday's suicide bombers created a precedent. If there were at least four on each aircraft, this means 16 men decided to kill themselves at the same time. Did they all know each other? Unlikely. Or did one of them know all the rest? For sure, they were educated. If the Boeing which hit the Pentagon was being flown by men with knives (presumably, the other three aircraft were too) then these were suicide bombers with a good working knowledge of the fly-by-wire instrument panel of one of the world's most sophisticated aircraft.
I found it oddly revealing when, a few hours later, an American reporter quizzed me about my conviction that these men must have made "dummy runs", must have travelled the same American Airlines and United Airlines scheduled flights many times. They would have to do that at least to check the X-ray security apparatus at airports. How many crew, the average passenger manifest, the average delays on departure times. They needed to see if the cabin crew locked the flight deck door. In my experience on US domestic flights this is rare. Savage, cruel these men were, but also, it seems, educated.
Like so many of our politicians who provide us with the same tired old promises about hunting down the guilty and, Mr Blair's contribution yesterday, "dismantle the machine of terror". But this misses the point. If the machinery is composed of knives and box-cutters, Mr Blair is after the wrong target. Just as President Ronald Reagan was in the hours before he ordered the bombing of Libya in 1986. "He can run, but he can't hide," he said of Colonel Muammar Gaddafi. But Colonel Gaddafi could hide, and he is still with us.
Instead of searching for more rogue states, President George W Bush's reference to those who stand behind the bombers opens the way for more cruise missiles aimed at Iraq or Afghanistan, or wherever he thinks the "godfathers of terrorism may be". The Americans might do better to find out who taught these vicious men to fly a Boeing 767.
Which Middle East airlines train their pilots for this aircraft? Indeed which nations are generous in their pilot-training schemes for Third World countries? I recall one of Iran's best post-revolutionary helicopter pilots telling me he was given a full course on the Bell Augusta (the Vietnam-era gunship) by the Pakistan air force, which itself paid retired American pilots to teach them.
And if Osama bin Laden is behind the New York massacre, it's worth remembering one of his aims: not just to evict the US from the Middle East but to overthrow the Arab regimes loyal to Washington.
Saudi Arabia was top of the list when I last spoke to him, but President Hosni Mubarak's Egypt and Jordan, ruled by King Abdullah II, were among his other enemies. He would keep talking about how the Muslims of these nations would rise up against their corrupt rulers. A slaughter by the US in retaliation for the New York and Washington bloodbaths might just move the Arab masses from stubborn docility to the point of detonation.
Within the region, the suicide bomber is now admired. Not because he is a mass killer but because something invincible, something untouchable, something that has always dictated the rules without taking responsibility for the results, has now proved vulnerable. It was the same when the first suicide bombers struck in Lebanon.
The Lebanese could scarcely believe that Israeli soldiers could die on this scale. The Israeli army of song and legend had been brought low. So, too, the reaction when the symbols of America's pride and power were struck. The vile, if small, Palestinian "celebrations" were a symptom of this, albeit unrepresentative. They matched the "bomb Baghdad into the Dark Ages" rhetoric we heard from the American public a decade ago.
In the Middle East, Arabs now fear America will strike them without waiting for proof, or act on the most flimsy of evidence. For it is as well to remember how the US responded to the 1983 Marine bombings. The battleship USS New Jersey fired its automobile-sized shells into the Chouf Mountains, killing a couple of Syrian soldiers and erasing half a village. The arrival of US naval craft off the American East Coast yesterday was a ghostly replay of this impotent event.
But to this day, the Americans have never discovered the identity of the man who drove a truck-load of explosives into the Beirut Marine compound. That was in another country, in another time. Today's suicide bombers are a different breed. Nurtured in whatever despair or misery or perhaps even privilege, in 2001, the suicide bomber came of age.