KANDAHAR - We heard the news early in the day. Three more Canadian soldiers had been killed by a roadside bomb, but it was many hours before the families had all been notified and we were given the details of what happened.

They were riding in a dune buggy.

Or, "a green golf cart, with a big bin in the back," as Battle Group Commander, Lieutenant-Colonel Rob Walker described it. In reality, it's called an M-Gator and it's made by John Deere.

One of the soldiers, Sergeant Cristos Karigiannis, was a qualified U.S. army ranger, an avid paratrooper, and in the words of his battalion commander, "exactly the type of soldier that we look up to."

Extremely talented. Very personable. Very fit.

"He was the epitome of a Canadian non-commissioned officer. He led from the front. He wouldn't let his soldiers do anything that he wouldn't do first."

So what was he doing driving through a combat zone in an open dune buggy, with two other soldiers?

Was it a security lapse? Over confidence?

The answer reflects the day-to-day challenges and danger that Canadian troops face in Afghanistan, and the calculated decisions that officers have to make.

The three soldiers were delivering supplies, probably water and rations between two checkpoints, in an area that Canadians had tamed last summer and considered relatively secure. In fact, it was the only place in the entire Canadian zone considered safe enough to use such an exposed vehicle on re-supply missions.

"We were confident enough in our collective security assessment," says Lt-Colonel Walker, "and it was for that reason that we allowed -- I allowed -- the use of the Gator in that particular area."

And then three months after that decision, Taliban fighters slipped in during the night and planted their bomb, a combination of two-anti-tank mines, wired to an anti-personnel mine as the detonator.

The Gator and its passengers were an easy target.

The Canadian commander of Task Force Afghanistan, General Tim Grant called it an "unfortunate accident," and for a day or two, officers here vigorously defended the use of the Gator.

And those journalists, and pundits who questioned that it might not be the safest way to run supplies, were--at least in some minds--just a bunch of knuckleheads.

"Let's be clear about this," said Lieutenant-Colonel Wayne Eyre, who is another senior officer in Kandahar, and commander of the soldiers' battalion back home. The path was twisty and narrow, bordered with high mud walls, and if the soldiers couldn't use the Gator, he said, "they'd have the stuff on their backs and they'd be walking."

"So anybody with a little bit of understanding of this theatre, and a modicum of common sense would realize this is a viable way of moving, in the type of terrain they're dealing with."

A day later, Lt.-Colonel Walker, the Battle Group commander, announced that Gators would no longer be used for this kind of re-supply work.

He also offered a disturbing new assessment of the danger on the ground.

And here we're talking about the Panjwai district, considered a Canadian success story in the otherwise violent countryside around Kandahar City. The Taliban had been driven out, the soldiers had developed a good relationship with the tribal elders, a lot of money was spent on jobs and aid projects, and there hadn't been a bombing or an ambush for months.

Now says Walker, with recent attacks on an Afghan police unit, and the killing of the three Canadians "the security situation has changed abruptly."

He's not sure why the Taliban have returned, or what it means for the future, but he understands the threat. Specifically, the threat against his soldiers.

"They're saying: 'We're not gone, and we're targeting you.'"