Would he be able to wear it on a CAP uniform?

[JeffDG]

http://www.ottawacitizen.com/news/canada-in-afghanistan/Canada+hands+military+honour+general/5266542/story.html

OTTAWA — The former top U.S. military commander in Iraq and Afghanistan is being honoured for his service by Canada's commander-in-chief.

Gov.-Gen. David Johnston will give a meritorious service decoration to U.S. Gen. David Petraeus for his work with "Canadian Forces members engaged in combat operations in Afghanistan."

[Persona non grata]

Yes

[Sapper168]

I would agree, it would fall under the Foreign military awards