Canadian soldiers are coming under specific and repeated threats during their patrols on the streets of Kabul, Afghanistan, their commander says.

"We had a bomb threat last night that was passed to us by Afghan national authorities," Maj.-Gen. Andew Leslie said Tuesday.

It isn't the first such threat since Canadian forces have faced since they joined the International Security Assistance Force (ISAF) mission in Afghanistan's capital city, he said.

"The threats are essentially two-fold. One is the threat of suicide attacks using car bombs or remotely exploded devices and the second is direct action, combat action against ISAF patrols."

The threats don't come as a surprise. Counter-intelligence officers say they expected Canadian troops to be targeted early in their mission because the were still learning their jobs, making them more vulnerable.

CTV reporter Matt McClure, embedded with Canadian troops in Kabul, says it's clear the forces are taking precautions.

"There is a heightened sense of security," McClure told Canada AM Wednesday. "When they're out on patrol they're extra, extra vigilant -- on the lookout for vehicles on the side of roads that could be concealing explosives.

"But that said, the Canadian commanders are adamant they're not going to let those threats prevent them from getting out and doing the job they're here to do."

Despite the dangers, Canadian soldiers are still on the streets, guarded closely by their light armoured vehicles.

When they come back from a day of running vehicle checkpoints, however, there's a sense of relief.

"Everybody is safe right now and we're well trained and if we follow our training … things should work out in the end," said Maj. Kevin Caldwell, commander of Charles Company.

While commanders try to put a reassuring face on things, there is evidence the strains of the mission are affecting the troops.

At least six Canadian soldiers have been sent home for medical or fitness reasons. To put that in context, there are about 1,850 Canadian soldiers in Afghanistan.

Privately, soldiers are surprised at the medical leaves, given the degree of screening and preparation they went through before shipping off. They also note there have been no major incidents so far.

Conditions are difficult. Daytime highs can reach 40 degrees Celsius, and dust storms can reduce visibility to almost zero.

Col. Mark Hodgson said while the screening system works quite well, there are a few soldiers who aren't completely up front during the interview process and who are now being caught out.

A major effort has been made to make Canada's home base in Kabul a comfortable place.

Soldiers have acess to a 24-hour-per-day Internet cafe, they can lift weights in a fitness room, and have a games lounge.

As a result, Maj. Jordan Rice, the base's social worker, said morale among most is quite high, although that could change if some soldiers get killed.

He offered this perspective on dealing with stressed-out soldiers: "One time, the way we treated combat stress casualties was we either court-martialled them or executed them. … We're evolving and we recognize that combat stress and critical incident stress is real."

The tragic deaths of four Canadian soldiers in a friendly fire incident in southern Afghanistan last year showed the importance of helping soldiers cope so they can remain effective, the army said.

Military officials predicted before this mission began that between five and 10 Canadian troops would die in Afghanistan over the next year.