OTTAWA -- The Canadian military insists that its bombing campaign in Iraq is being conducted according to international law, which means there are some targets that Canada's aircraft will not hit.

However, Navy Capt. Paul Forget says there's no way to know for certain if Canada's most recent two missions caused civilian casualties.

Previous military briefings on the Iraq mission have made it crystal clear that civilians were not harmed, but today's was different: Forget says the latest targets -- a building and enemy positions -- make it impossible to say for sure.

Forget, a spokesman for the country's operations command, wouldn't talk about what targets are off-limits for Canada's CF-18 fighters, which have conducted four strike missions in Iraq so far.

Coalition aircraft have been hitting a variety of military and economic targets, everything from tanks and trenches to enemy training camps and oil refineries.

So far, Canada has hit construction equipment being used to dig defensive positions, an artillery piece, a roadside bomb-making warehouse and a line of defensive enemy positions.