Bill Gertz — In Japan island defense, Mattis shifts China dispute focus

Although understated in most media accounts of the visit, perhaps the most significant statement by the retired four-star general was his reiteration of the US defense commitment to backing Japan in its dispute with China over the Senkaku Islands — islands China has claimed as its sovereign territory and calls the Diaoyou.

Mattis reaffirmed that the uninhabited islands that sit atop large reserves of undersea oil and gas coveted by both China and Japan are covered by the 1960 US-Japan Defense Treaty.

"It's the oil, stupid."

Same with the South China Sea.

Asia Times
In Japan island defense, Mattis shifts China dispute focus
Bill Gertz