How do we achieve that balance?
One question is, where do you draw the line? What you're saying is that there should be a line, that it's important that there be a line, so people know what the rules are.
We could have a situation, and DND might be one example, where one country is perhaps more concerned or more fearful or more willing to put resources into something that's a very slim risk. We may be drawn into it because they think it's a good idea and because they are our partner we have to go along. Do we see that? Are there any elements of cooperation that have that aspect to them?
North Korea, for example, is the alleged threat requiring missile defence—not the Russians.