peace treaty was signed in 1978, 1972 was joint talkings.
In 1930 China was weak and Japan had power so Japan took what it wanted to take until it went too far (the killing of so much chineese people in Nankin).
From Japan perspective : japaneese where not smart enough to understand they crossed the line with such killings and plunder.
Today China has the power (both in terms of army and economic) and Japan is weak in (both terms).
So China takes what it wants now until someone say : now you stop.
This helps japaneese to understand what it is to be weak and be subjected to the law of the strongest (but much much lighter than they did to China, no japaneese en masse killings so far)
The thing is nobody want to tell China "stop" as all big modern nations (Europe/USA) need economic relations with China.
Same thing for Putin ( big army and big gas stocks needed by Europe) and Ukrain (small under trained army and few economic power).
