To begin, I'll look as well at paragraph 4 of article 21 of the convention. Canada's position on this is that it constitutes an exhaustive list of the activities that are prohibited in the context of a combined operation with a non-state party.
Within that then, when we look at subparagraph 21.4(d), that isn't an absolute prohibition on expressly requesting the use of cluster munitions. It's a prohibition on doing so in the context where the choice of munition used is within the exclusive control of the state party, which is the Canadian Forces in this context.
That was a contentious aspect of the negotiations, and the words there were chosen for a very specific reason.
The key concern that led to that provision was that there may be circumstances in which an individual on the ground, who simply calls for “for effect” close air support or artillery support provided by another state will nonetheless be deemed to have, or could be seen to have, made an express request for the use of cluster munitions.
As an example, when a forward air controller—say a Canadian Forces member on the ground—calls in for close air support, they may well simply specify “for effect”, but when the aircraft shows up to the location, there will likely be communication between the pilot in that aircraft and the individual on the ground who has requested close air support and who may be told what type of munition is going to be delivered and be asked to authorize that. So their authorization or their request would certainly be considered an express request to use cluster munitions, whether they used the words “cluster munitions” or not. But they wouldn't, in that context, have exclusive control over the choice of munition used. That choice would have been made by the non-state party when they armed the aircraft.
Similarly, an individual calling for artillery support may call for it “for effect”. When the first round lands they'll know what they're getting, and if they provide revised coordinates or something further, that too might be seen as expressly requesting the use of cluster munitions. But again, the choice of munition used would be outside of the control of the Canadian Forces, or outside of the exclusive control, having been made by the non-state party.
That was the concern during the negotiations themselves and that's why subparagraph 21.4(d) doesn't simply read, “expressly request the use of cluster munitions”. That's why that second part of the subparagraph 21.4(d) is there, to recognize that there may actually be circumstances in which an express request is either made or deemed to have been made.