I suppose, if you're willing to believe your neighbor to the south will always be willing to come to your aid when you call. Even assuming your interests don't

I suppose, if you're willing to believe your neighbor to the south will always be willing to come to your aid when you call. Even assuming your interests don't conflict, that doesn't mean they'll always coincide. I wonder if, for example, the US would be willing to threaten Chinese fishing boats to protect Canadian fisheries, should it come to that. I'm thinking probably not. Also, the amount of influence you have in influencing policy in these international military coalitions depends in large part on how much you bring to the table. It's rarely, IMO, a good idea to get involved in coalition warfare, but you'd like to have the option if your country's interests would be served in doing so.