"It's for an anti-war rally. You are listed as a speaker. This is a joke, right?"

It hadn't occurred to me when I'd agreed to take part in a panel discussion about Iran and the US that I would be an anti-war poster child. But as the invitation to speak came from Richard BoydBarrett, and the Irish Anti-War Movement was sponsoring the debate, I suppose it might be interpreted that way.

Last week, I was reminded of that discussion when I saw the new American defence secretary Robert Gates quoted at a Pentagon news conference in response to questions about whether the United States is about to attack Iran.

"For the umpteenth time, we are not looking for an excuse to go to war with Iran, " he said. The New York Times doesn't say he turned red and flapped his arms for emphasis, but the exasperation comes through just the same. "We are not planning a war with Iran."

When I sat in an overheated upstairs ballroom in a Northside hotel last June, flanked by Michael McClennan of the US embassy and Richard Waghorne (now of the Mail), debating some less unusual suspects for attendees at an anti-war event, I was there reluctantly. Basically, I thought then that a US strike on Tehran is slightly less likely than a manned mission to Mars in this decade. For badness, when asked by moderator Vincent Browne who was the bigger nuclear threat, the US or Iran, I even opted for 'the US' - for the same reason that, if I have a rock and you don't, I am by at least one plausible measure a bigger 'rock threat'.

Since that debate, the number of issues increasing tension between the US and Tehran's Shiite radical theocracy in Tehran has doubled. While Iran's nuclear programme continues to trundle along, unimpressed with European efforts at diplomacy, there is also evidence that US soldiers are being killed in Iraq by weapons purchased by or manufactured in Iran.

Sniper rifles with armourpiercing rounds, capable of going through body armour, armoured cars or a helicopter, from a batch purchased from an Austrian gunmaker by Iran have turned up in Iraq. So too explosives used in roadside bombs against US patrols.

The debate in Washington is somewhat surreal. There are commentators on the right who say a showdown with Iran is inevitable.

It is easy to laugh them off to some extent, because many of them were the biggest advocates of the Iraq misadventure, which, to put it mildly, hasn't worked out as they'd hoped. But a nuclear-armed Iran scares the bejaysus out of people across the political spectrum.

Then again, there remains a question about what the US can actually do, militarily, to prevent it. The Pentagon's phone is going straight to voicemail at the moment.

Nonetheless, there is now a danger that the US will be even less able to extract itself from Iraq. If it's beyond doubt that Iran, at the highest levels, is already at war, via proxies, with the US, Washington faces a dilemma even worse than before - it may be already embroiled in a regional conflict. There are even reports that actual personnel from the so-called Quds force, a branch of Iran's revolutionary guard, are actively involved in operations against the US in Iran - which gets closer to direct conflict between the two countries.

It is, of course, in the interest of Iran to provoke an attack from the US. It would shore up support for the regime at home, because Tehran understands that while the US is tied down in Afghanistan and Iraq, it poses no mortal threat to the Iranian revolution. So an equally good outcome would be to keep the US tied down in Iraq as long as possible.

And because of the Iraq debacle, the burden of proof on the US intelligence necessary to prove an Iran connection is impossibly great.

Still, the odds of a conflict are shortening. And I see they might be moving forward plans for that Mars mission.