If you aren't willing to move to conflict (or whatever the next step is) at some point, then you are, in fact, just bluffing, and you are being called out on that bluff.

You can choose what that point is, but it's weird not to expect enemies to continually test where your line is, and walk you right up to it.

I'm not sure what you expect to see here?

Let's assume for a second armed conflict is the "natural" next step.

Either you are willing to get into an armed conflict over it or not. If you aren't, and they are willing to accept everything other than armed conflict (sanctions, etc), why should they care at all what you think or do? They already know you won't escalate past a certain point. As long as they are willing to accept how far you are willing to escalate, ....

In the end, people monitor actions, not words.