I've lost count of the times I've been told - always on excellent, but unnameable authority - that Osama bin Laden is already in American hands and that the Bush administration is waiting for the right moment to announce his capture.

Ronald Reagan's body was on ice for many months, and his death was only announced when it became necessary to drive Abu Ghraib off the front page. Everybody knows, or thinks they know, that the administration will manipulate the intricate bells and whistles of homeland security to ensure the president's re-election. If terrorists don't strike in the run-up to November 2 (as most people assume they will) the level of alert will be jigged up to red, arrests will be made, the country will be declared saved from an evil plot and mass casualties, and Bush will storm past Kerry in the polls.

Much the most interesting thing about this last story is the character of my informant - not, as usual, Jack talking from the barbecue pit, but the sober and conservative New Republic, a magazine fiercely pro-Israel, which enthusiastically supported the invasion of Iraq. A respected senior editor, John B Judis, is one of the three authors of the July Surprise? piece in the July 19 issue. Conspiracy theorising is coming out of the internet closet and going mainstream. Or, to put it another way, conspiracy theorising is fast becoming a legitimate means of reporting on a government so secretive that unnamed Pakistani security types may well be the best informed sources on the Bush administration's domestic policies and strategems.

Even before September 11, secrecy was this administration's hallmark, as when it invoked the principle of executive privilege to conceal from public view the proceedings of vice-president Cheney's energy taskforce. After 9/11, secrecy was advanced, proudly, as a guiding principle for a nation at war. In his address to the joint session of Congress on September 20 2001, Bush spoke of a new kind of war, "unlike any other we have ever known", that would include "covert operations, secret even in success." Donald Rumsfeld quoted Winston Churchill to the effect that in war "truth must be protected with a bodyguard of lies". Dick Cheney talked of a war to be fought "in the shadows: This is a mean, nasty, dangerous, dirty business. We have to operate in that arena". The great fear, shared by people not customarily given to paranoia, is that the Bush administration has taken these tactics for conducting a secret, asymmetric war and applied them wholesale to the day-to-day governance of the US.

To live in America now - at least to live in a port city like Seattle - is to be surrounded by the machinery and rhetoric of covert war, in which everyone must be treated as a potential enemy until they can prove themselves a friend. Surveillance and security devices are everywhere: the spreading epidemic of razor wire, the warnings in public libraries that the FBI can demand to know what books you're borrowing, the Humvee laden with troops in combat fatigues, the Coast Guard gunboats patrolling the bay, the pat-down searches and x-ray machines, the nondescript grey boxes, equipped with radio antennae, that are meant to sniff out pathogens in the air. It's difficult to leave the house now without encountering at least one of these reminders that we are being watched and that we live in deadly peril - though in peril of quite what is hard to say.

On May 26 - a black day for sallow-skinned grocers and news vendors - the attorney general, John Ashcroft, flanked by FBI director, Robert S Mueller, called a press conference to tell the nation of some "disturbing intelligence" that he'd recently received: preparations for an attack on the mainland US were 90% complete; likely targets included the upcoming G8 summit in Georgia, July 4 celebrations, and the Democratic and Republican conventions in Boston and New York. Al-Qaida intended to "hit America hard". Mueller produced seven mugshots - six were of men of, as they say, Middle Eastern appearance - and told us to keep a sharp lookout for these "armed and dangerous" characters. For a few hours, the country shivered in anticipation of the horror about to descend on it, and phone lines to the FBI were jammed with excited descriptions of neighbourhood news vendors and grocers.

Ashcroft's performance confirmed the suspicion held by many that the Bush administration is in the cynical business of spreading generalised, promiscuous anxiety through the American populace, a sense of imminent but inexact catastrophe, for reasons that may have little to do with national security and much to do with political advantage.

... Obsession with secrecy is a contagion directly transmitted from government to people. Just as the administration now moves in Cheney's arena of shadows, so masses of ordinary Americans are seeing themselves as self-appointed master-spies, keeping watch on their government in the same covert way that the government supposedly keeps watch on al-Qaida. The backyard barbecue sounds like a convention of spooks. "Chatter" has been heard, though its source can't be revealed ... In such talk, Bush, Cheney & co are held to be as scheming, devious and hard to catch as Bin Laden himself.

This is an extraordinary moment in American history. Half the country - including all the people I know best - believes it is trembling on the very lip of outright tyranny, while the other half believes that only the Bush administration stands between it and national collapse into atheism, socialism, black helicopters, and gay marriage. November 2 looms as a date of dreadful consequence. A bumper sticker, popular among the sort of people I hang out with, reads: Bush-Cheney '04 - The Last Vote You'll Ever Have To Cast. That's funny, but it belongs to the genre of humour in which the laugh is likely to die in your throat - and none of the people who sport the sticker on their cars are smiling. They are too busy airing conspiracy theories, which may or may not turn out to be theories.