Aera magazine reported that, unbeknownst to the current DPJ administration, a previous LDP administration had made a secret agreement with China on how to deal with Chinese vessels that approach the Senkaku Islands.
“Under the secret promises, Japan was in principle to prevent landings (of Chinese nationals) on the islets and not to detain them unless it develops into a case of grave concerns," said Aera.
“The Chinese side promised to block (anti-Japanese) protesters’ boats from sailing off to reach the islands.”
Presumably, China used the violation of this agreement as a pretext for getting really, really angry. But I think this whole thing was staged by China, Japan, and America in an attempt to change things back to the way they were before the Hatoyama administration.
This will not stand.