The sting and the spin: will a small house in Willesden unlock the secrets of al-Qa'ida?

Eleven men are being interrogated in Paddington Green police station. One of them may be al-Qa'ida's 'UK general'. Is this a genuine intelligence breakthrough or another murky chapter in the war on terror?

When the US Homeland Security Secretary, Tom Ridge, stood under the glare of the television lights in Washington a week ago and announced the latest terror alert, a series of events began that seem like episodes from an airport novel.

Barricades were erected in several US cities, surveillance of suspects in London was stepped up, and, as we later learned, an al-Qa'ida computer expert went on emailing his UK contacts under the supervision of Pakistani intelligence. Then there was a wave of arrests in Britain, headlines about a plot to blow up Heathrow airport, police were said to be questioning the leader of a UK terror cell, and revelations about what was on the laptop computers of "significant" figures in al-Qa'ida's attack planning unit. It all read, with enough detail to lend verité, like one of the new breed of terrorism thrillers. Except for one thing. It wasn't the whole book, just a few tantalising chapters. What, then, is the whole story?

Mr Ridge announced on Sunday that the US had "new and unusually specific information about where al-Qa'ida would like to attack". He said it related to al-Qa'ida surveillance of at least five financial institutions in Washington, New York and Newark, New Jersey.

The message was clear: this information was new, up to date and relevant. Overnight, security at these locations was ramped up, bridges were closed in New York and roads around the Capitol building in Washington were blocked. It is likely these will remain in place until after November's election. In London US companies, including Citigroup based in Canary Wharf, stepped up security. One was said to have received a fax from its US headquarters asking if its "armed response units" were in place.

Mr Ridge, a former governor of Pennsylvania, is not a neo-conservative himself, but there were enough elements of the party political broadcast in his press conference - he went out of his way to praise President Bush's "strong leadership" - to set sceptical minds running. And within 24 hours, the doubters had their ammunition: the information upon which the warnings were based was three or four years old. As such it predated the attacks of 11 September 2001. One senior law enforcement official told the Washington Post: "There is nothing right now that we're hearing that is new. Why did we go to this level? I still don't know."

It seemed as if once again a terror alert would come and go leaving people on both sides of the Atlantic a little more scared, a little more bewildered and - dangerously - a little less likely to pay attention next time. But even as the argument raged over whether the Bush administration was "hyping" the terror issue, startling information about what had prompted the alert began to emerge 7,000 miles away in Pakistan.

The genesis of last week's events can be traced to an aborted attack on a Pakistani general in Karachi on 10 June. The bloodstained van used in the attack led police to three young militants who, it was discovered, had all been trained at an al-Qa'ida camp in the badlands of South Waziristan on Pakistan's frontier with Afghanistan.

Under interrogation one identified a Mohammed Naeem Noor Khan. At first there was little to suggest this 25-year-old son of an airline purser was an international terrorist. The computer expert and sometime student in Britain had excelled at school and university and was, on the surface, a respectable member of society. Further investigation, however, revealed that Mr Khan was intimately linked with al-Qa'ida - even to the extent that his marriage to the daughter of a Taliban leader had been arranged by the network for him. He was watched and then, when he tried to buy an airline ticket for Ahmed Khlafan Ghailiani, a Tanzanian wanted in connection with US embassy bombings in Africa, both he and, subsequently, the African were arrested.

But it was only when Pakistani intelligence agents found the two men's lap-top computers that the true extent of their prize became apparent. The hard disks carried plans of intended targets in great detail: traffic flows around Heathrow, traffic light sequences, explosives powerful enough to melt steel foundations, minute detail on the security arrangements of five major financial institutions in the US. Most valuable of all, however, was evidence of the terror network's internal communication system, evidently overseen by Mr Khan: a system of "dead-letter" email addresses and coded websites to communicate orders from the leadership around the world.

Intelligence officials realised that this network offered a golden opportunity to lure into the open those still answering the call of Osama bin Laden. A "sting operation" was mounted, as Mr Khan, whose capture was still a secret, was made to use his system to ask operatives to get in touch, revealing their whereabouts to his watching captors as they did so.

Who, if any, answered that treacherous message is not known but clearly by last weekend a decision was taken in Washington to end the covert operation. No terrorist would be replying to Mr Khan's fake emails once they realised what the US now knew.

Meanwhile, in London, the day after Mr Ridge's dramatic warning, a group of the country's most senior counter-terrorism experts gathered in Whitehall. The meeting, which included representatives from MI5, the Cabinet Office and senior police officers, including David Veness, the national co-ordinator on terrorist investigations, approved a major operation.

The next day the authorities moved against addresses up and down the country. By nightfall 13 men were held at Paddington Green police station. Reports that five others slipped through the net are denied by MI5 sources. Footage of the arrests - including images of men forced into the gutter at gunpoint - looked familiar. Minds went back to Crawley, Luton and other cases of people being held in some highly publicised swoop, amid blood-curdling warnings of national security being threatened, only for them to be released with considerably less fanfare days later. Public support for such roundups - particularly among the Muslim community - has been strained by obvious blunders such as the one that saw 10 arrested over an alleged plot to bomb Old Trafford. No such plot existed and all were later released, although not before two men had spent eight days in detention. Such over-reactions have led to an embarrassing mismatch between those arrested and those convicted of terror offences since 11 September: 609 to 15.

The authorities, both here and in Pakistan, are in no doubt that the operations of the last week are significant. The "terror alerts" may be questionable (much of the target surveillance predated 9/11), but the men picked up in Pakistan - and in at least two cases in London - are not unknown young fanatics living out some fantasy jihad, but figures of undoubted value. Pakistan's Interior Minister, Faisal Saleh Hayyat, said: "Al-Qa'ida is in a critical tailspin. It is only a matter of time before it is wiped out. But it does pose a real threat today."

The chief prize in London is a man now being described as Bin Laden's "UK general", Abu al-Hindi. Seized at a house in north-west London, Mr al-Hindi is said to have been traced from Mr Khan's computer. He is thought to have been under surveillance for a number of weeks and was the main target of Tuesday's operation. A slew of reports paint a picture of the man as a linchpin in the terror network. If they are all true, the man with the codename Bilal is one of three men who cased potential targets in the US, is the author of a guerrilla training manual and was a worshipper at Abu Hamza's Finsbury Park mosque.

Mr al-Hindi's home, in Chapter Road, Willesden, is in a row of two-storey Victorian terrace villas which are familiar throughout London's inner suburbs. His next door neighbour, David Bendar, 25, said he sometimes saw the man police accuse of being a senior al-Qa'ida recruiting agent kicking a football about in his garden. "He looked like a Europeanised man from the Middle East," he said. "He had short black hair and was clean-shaven and wore Western clothes. We would see him playing football with four or five other guys. Sometimes they sat and smoked a big pipe. They played Arabic music. I never spoke to him."

Inside the flat clothes remained strewn over the bed where the police had rummaged through wardrobes and drawers. It is a functional but not uncomfortable home. The floors are covered with beige wood laminate and the walls are painted beige. The only decoration is a Free Palestine poster and a clock set in a frame with an image of Mecca. Suitcases full of papers were laid open in the bedroom and in the small living room a full ashtray, two half-full coffee cups and an Arabic newspaper betrayed the surprise of Mr al-Hindi's capture. No charges had yet been laid against him yesterday. Police can hold him until tonight.

Details about a second man, also detained in London at the behest of the US authorities, emerged yesterday. Babar Ahmad is the website administrator at Imperial College, London, and is said to be a cousin of Mr Khan. If US prosecutors are to be believed, he ran websites raising funds for Islamic terrorism, had contacts with the Chechen rebels behind the Moscow theatre siege, and collected details of the vulnerability of the US Navy to attack. Mr Ahmad has already been arrested once in the UK, in 2003, but was released without charge despite allegedly being found in possession of US naval battle plans. The US authorities now believe they have enough evidence against him to issue their own warrant.

There has been considerable scepticism over the timing of these arrests in London and Pakistan. Just as the White House has been accused of timing its new orange alerts to undermine presidential challenger John Kerry, so the timing of the new arrests is suspiciously convenient for Pakistan. After all, they come just as President Pervez Musharraf was under renewed pressure, particularly after the many unflattering mentions Pakistan received in last month's 9/11 Commission report. Well-informed sources say Mr Musharraf was being pressured by the White House to help President Bush on one of two fronts: either to deliver new al-Qa'ida arrests, or provide troops for Iraq. And sure enough, just as the arrests were announced this week, Pakistan said it would not send troops to Iraq. The suspicion persists that Pakistan moves against al-Qa'ida only when the timing suits President Musharraf.

But whatever the spin, the key figure in the week's events - the man who triangulates the warnings in the US, the arrests in the UK and the leaks from Pakistan - is Mr Khan. American intelligence sources portray him as a crucial link in a global al-Qa'ida communication network, sending out orders from the group's leadership on the run in the Afghan-Pakistan border area to cells across the world. That is a very different picture from the one the Americans and the Pakistani authorities were presenting to the world before, of an al-Qa'ida that had been decimated in Pakistan, its operatives killed or captured, its leadership on the run in the remote border areas and unable to control anything.

The fact is that the "war on terror" has become so politicised and the popular portrayal of al-Qa'ida so warped (the phrase "linked to al-Qa'ida" has become a kind of journalistic knee-jerk) that very little - certainly in the short term - can be taken at face value. The politicisation is bound to be at its height in a US election year.

Frosting the glass through which events are viewed just as much is the idea of al-Qa'ida as a real-life Smersh, ready to strike at the snap of Bin Laden's fingers. The view from the experts has always been that the group was never a huge international organisation, but rather a small, mostly Arab group that had loose alliances with groups around the world. Recent bombings were believed to be the work of allied groups, whose militants were trained at al-Qa'ida camps in Afghanistan, but who did not receive direct orders from al-Qa'ida since the core group was badly hit in the American bombing of Afghanistan in 2001. As many as 80 per cent of the core group's membership was believed to have been killed or captured.

But the latest reports, if they are to be believed, suggest al-Qa'ida has survived the onslaught better than was previously thought and is still attempting to coordinate attacks around the world. The problem is determining where the facts stop and the spin begins. Two months ago, M J Gohel, a terrorism expert with the Asia-Pacific Foundation, told the Commons Foreign Affairs Committee: "Destroying al-Qa'ida alone will not resolve the problem. There is no central command, or a single individual, controlling all the terrorist groups but there is a central ideology - the destruction of the democratic and secular world. Al-Qa'ida should not be perceived as an organisation, but as a world movement."

The final complication is the position of the authorities in the US and Britain. After 9/11, Bali and Madrid, it would be a very brave - not to say foolhardy - official who didn't err on the side of issuing warnings first and downgrading them later.

After all, whatever successes may be achieved in arresting this computer operator or that courier, or another alleged leader of a further "terror cell", it takes very little money and no great planning to cause large-scale death and destruction if dedicated terrorists get lucky. And they may not do the authorities the favour of recording their intent in emails. Mr Gohel told the foreign affairs committee: "Targets may have been signalled in the past, but only in the context of endless additional signals, so that the truth is buried in a grave of lies. Therefore, there will be constant alerts and signals, but the attacks will continue to be unanticipated."

This is not quite the version the authorities would have you believe - or that the conspiracists cling to. But at least it is not fiction, airport or otherwise.

'Key al-Qa'ida operators' held in UK and Pakistan

Babar Ahmad

Age 30, born Pakistan. Cousin of Khan. Arrested in London, Thursday, on US extradition warrant accusing him of trying to raise funds for "acts of terrorism in Chechnya and Afghanistan" from 1998 until 2003. A computer specialist who, say US prosecutors, ran websites raising funds for Islamic terrorism, obtained secret documents detailing US navy vulnerability to attacks, and had email link to Chechen rebel leader behind Moscow theatre siege.

Ahmed Khalfan Ghailani

Reported to be in his early 30s, born Tanzania. Arrested 25 July in Gurjat, eastern Pakistan, after gun battle with police. Suspected of having masterminded the bombings of American embassies in Tanzania and Kenya in 1998 which killed 224. America had offered up to $25m reward for his capture. In May was named on list of seven al-Qa'ida operatives planning attack in the US this year. In custody in Pakistan, awaiting extradition decision.

Mohammed Naeem Noor Khan

Age 25, born Pakistan; holds Canadian passport. Arrested Lahore, 13 July. Computer expert who allegedly acted as communications link between al-Qa'ida leadership and cells. Arrested with a computer containing intelligence "treasure" providing "deep insights" into al-Qa'ida operations. After arrest he reportedly took part in a sting operation against his former comrades. In custody in Pakistan, awaiting decision on possible extradition to US.

Abu Eisa Al-Hindi

Reported to be in his late 20s to early 30s; born Pakistan. Arrested London, Tuesday. Said to be "key al-Qa'ida figure" in UK. Alleged to be one of three men sent on personal orders of Osama bin Laden to "case" important buildings in US in 2000 and 2001. Said to operate under codename Bilal; numerous aliases. Said to have worshipped at Finsbury Park Mosque, former HQ of cleric Abu Hamza, in custody awaiting extradition to US.

Katie Sutton

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