A pledge by Japan this week to provide a security guarantee for Ukraine alongside other allies is a reminder that Tokyo may be Europe’s most dependable defence partner in Asia.It also strengthens the argument for Nato to proceed with a long-discussed plan: opening a liaison office of the transatlantic security alliance in Tokyo.On Tuesday, Japanese Prime Minister Shigeru Ishiba declared that Japan would “thoroughly discuss what our nation can and should do” in support of Ukraine, and “play an...