[quote=So Boerd]
Point of some dispute.
[/quote]

It is; but it was very clear in negotiations that any aggression on the Continent was to be dealt with by the Signatories declaring war on the aggressor.

Even with the whole sphere of influence (which is debatable on whether you had it over that area), you just simply aggressively invaded Belgium. 
"--Section 2: A signatory has a responsibility to ensure that the humanitarian needs of those in their sphere of influence are met, and can request help from other signatories in order to meet this responsibility."

I would consider that breaking Section 2. Rather than attempting to do this peacably y'all just invaded without warning to the ToC signatories or Belgium.