Japan’s public diplomacy hovers between the ludicrous and the sinister. In recent months, the country has specialised in foreign policy gaffes that seem designed to give maximum offence to its Asian neighbours while causing maximum embarrassment to its western allies.

Last week provided another example. Japan unveiled the largest naval vessel it has built since the second world war. The ship is nominally a destroyer – but it is an aircraft carrier in all but name. Beefing up the Japanese navy is arguably a legitimate response to China’s arms build-up. But, at a time of rising tensions in Asian seas, Japan should tread carefully. So what genius decided to call this new ship “Izumo” – the same name as a Japanese warship that took part in the invasion of China in the 1930s?

China was quick to charge Japan with deliberate provocation. Such an accusation would be easier to brush aside if the naming of the Izumo was an isolated incident. But just a few days earlier Taro Aso, Japan’s deputy prime minister, was caught suggesting that the Nazis might provide a suitable model for efforts to revise Japan’s pacifist constitution. “We should proceed quietly,” Mr Aso mused. “One day people realised that the Weimar constitution had changed into the Nazi constitution. No one had noticed. Why don’t we learn from that approach?” The unsurprising outcry that greeted these remarks forced an official spokesman to issue a clarification: “The Abe administration does not perceive Nazi Germany in a positive light.”