Bob - not his real name - had agreed to the interview only on condition that it was off the record. He greeted my jokey, break-the-ice observations that military intelligence was an oxymoron and that it was the world's second-oldest profession, only with fewer morals than the oldest - prostitution - with a sharp intake of breath.
That was clearly the wrong approach to take with Bob, and he said so. He was talking only because the media claims about his buddies getting it wrong with Iraq, Libya, Iran, North Korea and all the rest had incensed him to the point that he wanted to set the record straight. Bob's voice dropped to a near whisper as he put his mobile phone as close to his mouth as possible. In my mind, he had pulled a sombrero over his face and slipped into the deepest shadows of the saguaro cactus he no doubt kept in his Washington office for such contingencies.
Intelligence was only as good as the access available and in cases where dictators held sway with an iron fist, getting it right 100 per cent of the time was impossible, he intoned. That is where satellites, heat detectors and the like came in and they were only as good as the technology on offer.
Such an obvious answer deserved an obvious response. How did that explain Pearl Harbour and the attacks on September 11, 2001? They were on home soil and proof that a near half-century of technological development of equipment and intelligence techniques had been worthless.
Bob was incensed. Evil was out there, everywhere, he thundered, then remembered that walls have ears in his line of business. His voice dropped to an angry whisper and he pointed out that his country knew who its enemies were, but they were devious and keeping a step ahead of them was like fighting a virus - they were ever present, ever mutating and always programmed to kill.
So what about these top-level inquiries into apparent intelligence failures in detecting Iraq's supposed weapons of mass destruction? The war had ended nine months ago, Saddam Hussein had been overthrown and still not a single chemical, biological or nuclear weapon had been revealed.
Bob must have been smiling as he answered, quoting US Defence Secretary Donald Rumsfeld's comments at a press conference earlier that day in the German city of Munich. 'The question is: is the glass half full or the glass half empty?' he mimicked.
Bob, like the governments facing barrages of questions over whether the war on Iraq was justified for the reasons given at the time, was apparently also in denial. A change of tack was necessary.
North Korea, as the only part of the 'axis of evil' still thumbing its nose at outside pressure, seemed like the best move. A series of reports in recent weeks from intelligence and human rights groups had indicated abuses taking place as bad, if not worse, than anything blamed on Hussein's regime.
The most tempered, from the London-based human rights group, Amnesty International, said the North Korean government had denied or restricted access to food for its people, causing hundreds of thousands to die in the past decade. Reports in the British media last weekend were more graphic, telling of a prison camp where babies were killed by guards stamping on their necks and chemical experiments were carried out on prisoners in gas chambers. The alleged evidence came from defectors to South Korea and documents stamped 'top secret' that they had smuggled out.
Bob changed his tone considerably. 'Some discretion with sources, particularly those with an axe to grind, is something I take seriously,' he said. 'I imagine that people who have defected from North Korea have been through the hands of many people and one cannot be particularly sure about the quality of information they give. There's virtually no way to verify it and the best way is to cross-check information - which is difficult when you're dealing with single sources.'
So, Bob, keeping Iraq firmly in the back of your mind, does the same sort of thinking apply to North Korea's claims that it has nuclear weapons? This sort of information can be used by one nation to invade another, right? A long pause. 'Well, that is worrisome, isn't it?' Bob admitted.
Given the human and financial costs of Iraq and Afghanistan, North Korea will not go the same way. The increased public scrutiny will mean the US and British governments will treat the information they receive from intelligence much more carefully.
Bob mumbled a meek farewell and the phone line clicked dead. Hopefully, as he slipped from his cactus hideaway and swapped his cumbersome headgear for a baseball cap and reflective-lensed sunglasses, he also felt humbled.
Peter Kammerer is the Post's foreign editor