I'm writing the document now. I also had a look again at what exactly Thenaca said, and it appears I misconstrued it. Joint military exercises, not mutual defense. Joint military exercises I'm fine with.
This does bring up a good idea, though- should a Commonwealth member be attacked by an outside force, should we put our commitments to the territorial integrity of other Commonwealth members into writing, or should it be more of an "unspoken law", not mentioned in the document?
The IRL Commonwealth did not include a mutual defense pact because, IIRC, of the strength of NATO. Since we don't have a strong super-alliance like that, but rather a bunch of different ones, do you guys think including mutual defense in our charter is worth it, or still not worth it?
tl;dr I'm not sure whether to include it or not and I wanna know what you guys think.