It sure sent a jolt through the United States. Yet last week's much ballyhooed arrest of the "dirty bomb" suspect Jose Padilla now seems, like other developments in the "war against terror", to have been a political device of the Bush administration – designed to distract attention from US intelligence failures and solidify support behind President Bush.

For who, exactly, is Mr Padilla, aka Abdullah al-Muhajir? Is he a highly trained al-Qa'ida operative who was about to explode a radioactive "dirty" bomb in Washington DC, as the US attorney general, John Ashcroft, would have us believe? Or a Chicago street punk of no great danger to anyone?

With each passing day, the latter looks more likely. No plot and no accomplices have been discovered, despite Mr Padilla having been in detention for more than a month before his existence was revealed to the nation, which duly panicked.

As the New York Times said on Thursday, quoting some of those unnamed "US officials" who abound in the nation's press, he was "an unlikely terrorist, a low-level gang member with no technical knowledge of nuclear materials who was arrested long before he represented a significant terrorist threat".

And why, if it was as important as Mr Ashcroft claimed, was his arrest kept secret for five weeks – only for the attorney general to reveal it while in Moscow of all places?

Some might claim the venue was oddly apt, though. With his fierce prosecutorial zeal and taste for scary hyperbole, Mr Ashcroft calls to mind Andrei Vyshinsky, the infamous prosecutor at Stalin's show trials, whose prime contribution to 20th-century legal doctrine was the "presumption of guilt" against those unfortunate enough to be in his sights.

For "enemy of the people" read "enemy combatant", as Mr Padilla, a US citizen, has now been designated. He sits in a naval prison in South Carolina, presumed guilty but not charged with any criminal offence. Indeed, Donald Rumsfeld, the Defence Secretary, has acknowledged that he may never be charged. Mr Padilla's lawyers responded to that statement with a petition to the courts, saying their client's detention without time limit or the right to counsel should be "a constitutional concern to everyone".

No one would dispute the US's right to defend itself against terrorists, nor that this shadowy struggle, "asymmetric" in the jargon of conflict experts, demands exceptional, equally shadowy means. But Mr Padilla's fate is currently shared by hundreds of non-Americans, mostly Arab individuals, swept up in dragnets in the days and weeks following 11 September, and nine months later still in detention on the most minor of charges. The only difference is, no one knows their names.

One thinks also of Lotfi Raissi, an Algerian pilot whose one stroke of good luck was to be arrested in Britain, not the US. He was picked up at his home near Heathrow airport on 21 September 2001, and Mr Ashcroft's Justice Department instantly demanded his extradition on the grounds that he had trained some of the 11 September hijackers.

But not a shred of evidence was ever forthcoming from Washington, beyond the fact that Mr Raissi was an Arab and had trained at an Arizona flight school at roughly the same time as Hani Hanjour, one of the hijackers of American Airlines Flight 77, which crashed into the Pentagon. In February he was released on bail, and in April his case was thrown out entirely. Had he been in the US, however, he would undoubtedly still be rotting quietly in jail.

But the fanfare around Mr Padilla served Mr Bush's purposes perfectly. Forgotten were the host of clues missed by the FBI and the CIA before 11 September. The US was on full nuclear terror alert, ready once more to take the President's word for anything and to support his plans for a new super-ministry for domestic security.

Recent "revelations" about Khalid Almidhar, another of the AA77 hijackers, are equally instructive, albeit for different reasons. More unnamed officials told Newsweek magazine that Almidhar was spotted by the CIA at a meeting of al-Qa'ida operatives in Malaysia in January 2000. But the CIA, it seemed, failed to alert other agencies, including the immigration services who might have picked him up on entry into the US.

But wait. A few days later, other intelligence sources disclosed, this time to the Washington Post, that the CIA had in fact told the FBI. By now an alert reader will have divined that the disclosures have less to do with the fight against terrorism than with the equally entrenched fight between the FBI and the CIA. And as armistice breaks out between them, in reaction to their having had their heads banged together by the Bush administration, blame is being shifted beyond US shores.

Take Khalid Shaikh Mohammed, the al-Qa'ida operative whom other anonymous counter-terrorism officials named early this month as a prime organiser of the 11 September attacks. Those officials claimed he was in Germany before the attacks, liaising with Mohamed Atta, who flew the jet into the north tower of the World Trade Centre.

The only problem is, the Germans know nothing about it – and when they ask Washington for further information, none is forthcoming. But that is a secondary consideration. The finger now points to Berlin, not Langley, where the CIA is based, or FBI headquarters in Washington. Increasingly, for the two secretive agencies engaged in the US's "war on terror", anything goes.


If the face fits...

Lotfi Raissi
Arrested: 21 September 2001.
Problem: Global coalition in doubt. Polls show America blames FBI and CIA for not stopping al-Qa'ida.
Solution: Arrests all over world, including this Algerian in England. Terrorism charges dropped after five months in prison.

Khalid Almidhar
Revealed: 4 June 2002.
Problem: Washington hearings begin, asking who knew what.
Solution: Press tipped off that CIA passed name and passport number of this future hijacker to FBI by email in January 2000.

Khalid Shaikh Mohammed
Reward offered: 5 June 2002.
Problem: Global condemnation of decision to photograph and fingerprint visitors from high-risk countries in Middle East.
Solution: FBI offers £18m reward for capture of this
37-year-old Kuwaiti, mastermind of 11 September attacks.

Abdullah al-Muhajir
"Arrested": 10 June 2002
Problem: Derision for new Department of Homeland Security. Unease about treatment of Arabs grows.
Solution: Arrest of this "dirty bomber" announced. But in reality he had been in custody for a month already