Canada apologizes and gives 10 million to someone who killed an American solider

[IceAgeComing]

Article 5 is used against sovereign states not terror organisations since to use it would be to imply that the latter are some way legitimate.  Besides; it'd also be incredibly hypocritical for a wide range of reasons - the first that comes to mind is that people from America were openly funding the IRA which were, eh, a terror organisation and under your argument America ought to have arrested them for Treason, which seems rather rediculous.

[IceAgeComing]

I note that the OP has done his normal thing of ignoring awkward points that he can't address.

So I'll ask more directly: should America have arrested people who directly funded the IRA for Treason?  Or indeed; those who gave weapons and support for the Mujahideen in the eighties?

[IceAgeComing]

If they tried to make war on the UK yes they should have .

Need I say more chaps, need I say more.  This shows how much this guy knows about the world outside his little Oregon bubble

[IceAgeComing]

The (small) number of British SS members (almost all from the Channel Islands due to the German occupation) got treated exactly the same as all POWs were at the time - as probably should have been the case.

There's also the fact that your ignoring: that treason is rebellion against your own state: so you can't commit treason against another country.  Like I can't commit treason against America or Belgium or whoever since those are not my country.