Yesterday marked the 70th anniversary of the Potsdam Declaration, which was issued by the United States, the United Kingdom and China in 1945 demanding Japan's unconditional surrender in World War II. As a cornerstone of the post-war international order and Japan's pacifist Constitution, the document makes it clear that the war Japan waged more than 70 years ago was an act of aggression.

Ironically, when asked to comment on this point in the Potsdam Declaration two months ago, Japanese Prime Minister Shinzo Abe refused to do so, saying he did not notice it in the declaration and could not say whether the war was right or wrong. He even retorted that accepting the declaration was just a way that Japan ended the war.

No surprisingly, Abe's ambiguous attitude is in line with his earlier efforts to weaken the worldwide consensus that Japan was an invader before and during WWII. During his first tenure as the prime minister from 2006 to 2007, he had claimed to get rid of the postwar system, which began with the issuance of the Potsdam Declaration.