On April 27, 2015, the United States and Japan signed the "New Defense Cooperation Guidelines"

1. The main contents of the defense cooperation guidelines

According to the new guidelines, Japan will Not only can it defend itself, but it can also protect allies like the United States. This is the first time in 18 years that the two countries have revised their defense cooperation guidelines. Related plans include lifting geographical restrictions on Japanese military activities.

The joint document related to the new guidelines clearly states, "The scope of application of Article 5 of the Japan-U.S. Security Treaty, which stipulates the obligation of the U.S. military to defend Japan, includes the Senkaku Islands in Okinawa Prefecture (i.e., China's Diaoyu Islands and its affiliated islands)."

2. Related background

US Secretary of State Kerry met with Japanese Foreign Minister Fumio Kishida in New York on April 27, 2015. Kerry emphasized that the United States recognizes Japan's sovereignty over islands in the East China Sea and that maritime security should not be left to the whims of major powers.

Kerry and Carter met with Japanese Foreign Minister Fumio Kishida and Defense Minister Gen Nakatani , in order to determine the exact content of the new defense guidelines before Japanese Prime Minister Shinzo Abe’s visit to the White House on April 28, 2015. The two countries also plan to strengthen cooperation in areas such as space and cybersecurity.

In the context of the Sino-Japanese island dispute, Japan announced in January 2015 that it would increase its military budget to a record level.

Reference

April 28: The United States and Japan agreed on new defense cooperation guidelines

/150428-2/

Foreign media : US Secretary of State Kerry threatened to help Japan "defend" the Diaoyu Islands_Military_China.com

/important/11132797/20150429/19605081.html