TOKYO - President Obama kicked off a tour of Asia on Wednesday with a pointed message to China and the entire region: The United States stands resolutely with Japan in a long dispute over some small islands in the East China Sea.

As Obama landed in Japan, news here was dominated by his comments to a Japanese newspaper that the string of islands subject to a bitter Chinese-Japanese dispute falls within the scope of a U.S.-Japan security treaty.

U.S. policy is clear, he said in written remarks to the Yomiuri Shimbun, that the uninhabited islands are administered by Japan and "therefore fall within the scope of Article 5 of the U.S.-Japan Treaty of Mutual Cooperation and Security."

Obama's statement affirmed longtime U.S. policy; Defense Secretary Chuck Hagel conveyed a similar message in November in a call with Japanese military officials. But by sending the message at the start of a weeklong trip to Japan, South Korea, Malaysia, and the Philippines, the president worked to reinforce a key purpose of his voyage, reassuring allies about U.S. commitment in a region anxious about China.

The Chinese government took offense at Obama's remarks. Foreign Ministry spokesman Qin Gang said the United States "should respect the facts, in a responsible manner abide by its commitment not to choose sides over a territorial sovereignty issue, be cautious on words and deeds, and earnestly play a constructive role for peace and stability in the region."

Obama isn't visiting China on this trip, but the country looms large as the United States looks to reassure Japan and others.

"We welcome the continuing rise of a China that is stable, prosperous and peaceful and plays a responsible role in global affairs," he told the Japanese newspaper. "Our engagement with China does not and will not come at the expense of Japan or any other ally."