Phase 0 is focused on prevention, and it can be argued that it was and is our phase 0 concept (long before it was called phase 0) that has significantly increased peace around the globe. Deterrence (in the form of fleixible deterrence operations) if needed, comes after phase 0, so you have actually seriously mischaracterized phase 0. All States will conduct shaping operations in peace, and that is what we do, and our intention is to mitigate issues that may lead to conflict or war. Regardless of what phase we're in we continue to conduct contingency planning, which most people would consider prudent.

Since zero isn't a real number, it isn't a real phase, it was simply a means to describe how we strive to maintain the peace.