There are two air policing missions in NATO: the Icelandic air policing and the Baltic air policing. Those are the two active air policing missions, and you've described them accurately. They're from NATO allies that don't have a fighter capability, and it has helped to promote the expression of their sovereignty.
We previously have done Icelandic air policing and in fact would likely contribute again to a policing mission in the future. As part of the NATO reassurance measures, though, NATO undertook to expand the size of the Baltic air policing mission, which essentially doubled it in size. A number of nations came in, and we're participating right now with Portugal in that. Within that expansion of the Baltic air policing mission, other NATO countries were invited, and Canada answered that call.