A newly leased Canadian Heron unmanned aerial vehicle sits on the tarmac at Kandahar Airfield waiting to take off for a surveillance mission. (Murray Brewster/Canadian Press)The next generation of unmanned aircraft in the Canadian military will be armed but will be used selectively and within the boundaries of international law, says the head of the country's air force.

"Armed unmanned aerial vehicles [UAVs] with air to ground weapons are a valuable capability and it's a good option to have and it is a good option for Canadians to have," said Lt.-Gen. Angus Watt.

Watt was at Kandahar Airfield to officially declare Canada's new air wing in southern Afghanistan fully operational.

The U.S. already operates armed drones in Afghanistan — MQ-1 Predator and MQ-9 Reaper pilotless planes — for surveillance and to attack insurgent positions. Some of the Hellfire missile strikes have killed not only Taliban and al-Qaeda leaders but innocent civilians as well.

Attacking targets remotely is something Canadians will have to weigh carefully, Watt said.

"What we have to be very mindful of is that Canada very much respects the law of armed conflict and you have to satisfy a number of conditions before you drop a weapon on anything," he said.

"And in the case of the UAV, those conditions will be very difficult to satisfy, but it will also be a very useful option to have."

Canadian air wing flying Israeli-made Herons

Watt made the comments on Tuesday, but for security reasons the interview couldn't be made public until he had left the region.

Canadian Lt.-Gen. Angus Watt, chief of the air staff, left, walks with two unidentified staff members at Kandahar Airfield on Tuesday. (Murray Brewster/Canadian Press)He is the first senior military officially to speak publicly about the plan, although the federal government signalled to the defence industry last year that it intended to eventually buy armed drones.

The Canadian air wing in Kandahar has started flying Israeli-made Heron unmanned aircraft, which are capable of carrying weapons.

But Watt said there's no plan to arm the Herons, which were acquired as part of the Manley commission report under a two-year, $94-million lease involving MacDonald Dettwiler and Associates in Richmond, B.C.

Prior to the findings of the independent panel, the air force had been working on a long-term strategy to acquire UAVs — known as the Joint UAV Surveillance and Target Acquisition System, or JUSTAS.

Last fall, the federal government laid out plans to the defence industry for a $500-million program that could potentially see the first long-range, high-tech drone delivered by early 2012.

The air force envisions rolling out JUSTAS in stages, with UAVs for overseas operations coming first, followed by domestic drones, including ones to patrol the country's three coastlines.

Watt, a former Sea King pilot and a 37-year veteran of the air force, had initially been skepitical of attack drones, but said his concern related to the ability of pilotless planes to operate in civilian airspace.

The technology has not evolved to the point where UAVs can automatically avoid other aircraft in the same area but Watt said he believes that problem will be solved within a decade.

The air force has operated pilotless surveillance planes for the last six years, beginning with the Spewer, a triangle-shaped aircraft launched from rails and nicknamed the flying lawn mower by soldiers who hear it coming from a distance.

The Spewer is soon to be retired, but the experience has taught some valuable lessons, Watt said.

"They provide essential information that saves soldiers lives on the ground," he said.