"A lot of the placards I make ask probing questions," says Martin Schweiger, a consultant doctor from Bradford, gripping an umbrella. "And I try to catch the soldiers' eyes as they drive out. I don't want to see the good people round here lose their jobs, but this base is the gunsight for the biggest weapons system in the world."
We're standing in the floodlit rain outside the gates of US-run RAF Menwith Hill, the largest spy base in the world. Its 26 enormous golf-ball radomes, or radar-domes, crop like acne on the Yorkshire hilltop five miles west of Harrogate. "I was trained as a doctor to prevent harm, and these weapons systems take money desperately needed for the world's health," says Schweiger and dashes to thank a policeman for ticking off a marine leaving without a seat belt.
Hopping from one foot to the other to the sound of an accordion is the veteran peace campaigner Lindis Percy. She has been arrested hundreds of times and served several traumatic sentences in Holloway for breaking into US airbases. A government file noted that "she seeks to test, check and embarrass MoD whenever she can". She has been detained the previous night, and her bail conditions forbid her from being stationary near the perimeter fence - hence the jigging.
Most members of her group, the Campaign for the Accountability of American Bases, are Quakers and they regularly hold services outside the base. They lack the ideological rhetoric of their counterparts in the Stop the War Coalition, but have doggedly turned out on the icy strip of pavement every week for six years. Through numerous court appearances, questions in parliament via Norman Baker MP, and the theft of documents from the bins, she has gradually pieced together the story of what the 1,400 US personnel are doing there.
Established in 1960 and operated by the US National Security Agency, Menwith Hill hosts dishes for the Echelon espionage system, which is reportedly able to intercept two million telephone calls and emails an hour from around the world. It pinpointed Iraqi positions and guided troop movements during both Gulf wars, and has been implicated in commercial espionage.
In July, the Defence Secretary, Des Browne, informed parliament that Menwith Hill would be incorporated in the US Ballistic Missile Defence (BMD) system, a global network of bases that will detect and shoot down missiles launched against the United States. The base will relay launches detected by satellite to US Space Command in Colorado. In addition, a new early-warning radar at RAF Fylingdales on the North York Moors was due to be switched on in August. Five British com panies, including BAE Systems, will work on the BMD project, which has so far cost more than $90bn. Until the announcement, the government had refused to confirm Menwith Hill's role in missile defence. Percy first spotted the planning applications for two radomes for the Space-Based Infrared System used to detect missiles ("the eyes of the viper", the US military calls it), filed at Harrogate in 1997. She attempted, but failed, to get a high court injunction against their construction.
Interceptor missiles have been deployed in California and Alaska, and while Poland remains the likely host of the European leg, Browne told parliament that the option of siting interceptor missiles in Britain would be kept "under review". Last year, Lt Gen Henry Obering, head of the US Missile Defence Agency, told a press conference that Britain had been identified as a possible host; this year Downing Street confirmed Tony Blair had lobbied George Bush to choose Britain, with a hope to having the system in place by 2012.
"This certainly places Britain on the front line in any future conflict," says Kate Hudson, chair of CND. "In the event of a war with the US, any country will wish to knock out the facilities in a pre-emptive strike."
Missile defence is central to Joint Vision 2020, the Pentagon's blueprint that outlined the principle of "full spectrum dominance" - the ability "to defeat any adversary and control any situation". The neoconservative think tank Project for the New American Century, whose members have dominated the Bush administration, called for such a programme "as a secure basis for US power projection around the world" in 2000.
This is what has pushed Russia on to a Cold War footing in recent months. Vladimir Putin has torn up treaties banning strategic bombing flights and limiting arms deployments in Europe, and has announced plans to restore mass production of military aircraft. In February, he spoke icily of the need to end "the world of one master, one sovereign" asserted by Washington, and this summer sent submarines to lay claim to a chunk of the Arctic.
This is not purely sabre-rattling for domestic consumption, but a direct response to the distortion of the nuclear balance of power that kept Cold War tensions in check. That equilibrium had been sustained by the Brezhnev-Nixon Anti-Ballistic Missile Treaty, restricting defence systems. Bush withdrew in 2002. Launching a nuclear first strike could soon become a lot safer for the US. "The age of balance is over," says Kate Hudson. "This will be the realisation of a long- standing US goal - first-strike capacity without fear of retaliation."
The United States maintains that it needs the defence system to protect it against threats from "rogue states" such as Iran, which it claims is pursuing in tercontinental ballistic missile technology. Defence analysts are sceptical. "North Korea was neutralised through diplomacy, and Iran is up to 20 years from delivering a nuclear warhead. Both countries could be flattened by Nato. It beggars belief that the US would need this," says Ian Davis of the British American Security Information Council.
The siting of interceptors in central Europe is particularly provocative to the Kremlin, coming after the leaking of a Pentagon report in 2002 that included Russia and China on a "nuclear hit list". Putin has pledged to overhaul Russia's 2,000-piece nuclear arsenal, and promised a similar air defence system against Europe. A senior Russian general bluntly warned the Czech Republic that hosting US radar would be "a big mistake".
One more occupation
With a military budget one-twentieth that of the United States, Russia cannot hope to assert the influence it once had. What is significant, however, is its return to Cold War strategies. "For Russia, missile defence is the final humiliation," says Davis. "First-strike scenarios may seem fanciful, but it's the thinking that prevails in the Pentagon and the Kremlin."
Back in Harrogate, there is popular suspicion of the base; the MP's caseworker tells me our telephone conversation is probably being listened to in Maryland. But well-paid Americans bring £65m a year to the town's economy; many send their children to local schools. "The base is very ugly, but the only complaints I get are about these protesters on day trips from Leeds," says John Fort, a local councillor.
People living in the shadow of missile defence installations in central Europe aren't so relaxed. In March, the Czech village of Trokavec voted against hosting a US early-warning radar. Despite strong support from the government, public opposition to the programme in the Czech Republic runs at 70 per cent."It's at the top of the popular political agenda," says Ivona Novometska of the No Bases movement. "Our politicians are extremely pro-US and still see Russia as some red devil. But after the revolution we were promised no more foreign soldiers on our soil, and the Czechs are starting to feel missile defence is one more occupation."
Despite the general enthusiasm of Europe's governments to sign up, it could be the United States itself that postpones "full spectrum dominance". In July, Congress slashed funding for an interceptor system in Poland. The technology behind "hitting a bullet with a bullet" is proving more elusive and expensive than first envisaged.
But Lindis Percy may be hopping outside Menwith Hill for a while yet.