China is trying to find a wedge between the Japanese / American alliance. And they have rightly diagnosed Obama as a weak leader. The U.S. should have declared these islands as under Japanese control and not merely ‘administration’. That left an opening for China.
The main problem for China is none of their neighbors like them and they will over reach. Overall, it looks like they are itching for a war. And I’m not sure the American people or its president have the backbone to commit to their treaty obligations.
Yes, the Chinese have rightly diagnosed Obama as a weak leader, so they are creating this opportunity to see how weak he is.