We were treaty bound not to engage in the north. We were not treaty bound in any manner for the south. We were very careful about that.
We broke no treaty by engaging Carelia. Plus, our engagement with Carelia would have been because they sent troops north to fight us shortly beforehand.
If you were within your rights, then why the excuses? Coria sure went to some lengths to try to pass off what they were doing as anything but engaging Carelia... The excuse Saeculo came up with was epic for its complete absurdity.