Before the invasion, when they had surrounded Ukraine, it might have been possible [to avoid war]. If [Ukrainian president Volodymyr] Zelensky could have been made to promise that his country will not join NATO, or made to grant a high degree of autonomy to the two enclaves in the east. I understand this would be hard to do—perhaps an American leader could have done it. But of course [Zelensky] would refuse.

https://www.economist.com/AbeInterview