He said this in an interview with the American portal Newsweek.
"If we say that we would not in practice see Ukraine as a member of NATO after this war, it would mean that we are afraid—or predict that—Russia will attack again and then NATO countries will be involved in a world war, or at least a war over the European continent. This is already admitting that large-scale war will repeat itself," Reinsalu said.
He rejected any alternatives to Ukraine's membership in the Alliance, including a plan for rapprochement with NATO in exchange for Kyiv's greater willingness to negotiate with Russia, which the media reported was being promoted by Britain, Germany, and France.
"What's the point of trying to copy NATO if you are making it clear that it is not NATO? It's like a half-NATO. I would be rather suspicious of that replica. Honestly, the only guarantee except NATO would be to deliver nuclear weapons to Ukraine," Reinsalu said, stressing that such a move is impossible, and undesirable, given the anti-proliferation commitments of NATO's nuclear powers.
According to Reinsalu, leaving Ukraine outside the West's security umbrella would leave Kyiv in limbo and undermine the country's recovery.
"Imagine we are not giving Article Five-based guarantees to Ukraine after the war. So, we will then encourage Ukraine to establish their self-defense in a 'hedgehog strategy,' like they are in the Wild West, standing in their fort with rifles and waiting for Russia. I think it will create a grey zone in the midst of Europe. It would be a grand negative signal on their aspirations towards the European Union, from the security perspective, about investment assurances, and everything else," the Estonian Foreign Minister added.