Answer:
The question asks for your own opinion, so I would just pick a side that you agree with the most.
If you think that America is at fault, all you have to do is find a quote from one of the articles that supports your opinion. If you believe that Japan is to blame, you would need to find a quote that supports your opinion.
No one can tell you that you're wrong because opinions can only be supported, so just choose a side and find facts to support it :)