Its not a completely unreasonable stance to take tbh. When your looking at radar of a missile strike coming in theres really no way to garuntee the payloads are conventional when the missiles are provided by a nuclear state. And with how close Ukraine is and how fast modern missiles are it doesnt give you much time to figure it out. A big part of nuclear war doctrine is you try to launch first to disable your enemies launch capabilities. If Russia has even a passing concern their launch capabilities could be threatened they WILL launch. I really hope the idiots running the world are careful with this.