WASHINGTON (Reuters) - The head of the U.S. Pacific Command made his first visit on Wednesday to a Japanese radar station on the edge of the disputed East China Sea that Japan opened last year to the anger of its regional rival China.

The Commander of the U.S. Pacific Command, Admiral Harry Harris, waits to testify before a House Armed Services Committee hearing on "Military Assessment of the Security Challenges in the Indo-Asia-Pacific Region" on Capitol Hill in Washington, U.S, April 26, 2017. REUTERS/Yuri Gripas

Admiral Harry Harris visited the Yonaguni Coast Observation Unit on the southernmost of the Ryukyu Islands at the invitation of the chief of staff of Japan’s self-defense force, Admiral Katsutoshi Kawano, the U.S. Pacific Command said.

The visit was the first by either official to the camp, Pacific Command said in a statement, which added that in discussions in Tokyo the previous day, the two men stressed the importance of cooperation to address the threat posed by North Korea’s nuclear and ballistic missile capabilities.

Japan opened the Yonaguni facility last year, giving it a permanent intelligence-gathering post close to Taiwan and a group of islands disputed by Japan and China. The move drew an angry response from Beijing, whose help Washington has been soliciting to help rein in North Korea.

The base is at the western extreme of a string of Japanese islands in the East China Sea, 90 miles (150 km) south of disputed islands known as the Senkaku islands in Japan and the Diaoyu in China.

Japan has been mired in a territorial dispute with China over the East China Sea islands and Beijing has raised concerns among other neighbors with its assertive claim to most of the adjoining South China Sea.

China has accused Japan of hypocrisy in opening the base while criticizing Beijing’s militarization of islands in the South China Sea.

The Japanese listening post fits into a wider military buildup along the island chain, which stretches 870 miles (1,400 km) from the Japanese mainland. Japanese policymakers have said it is part of a strategy to keep China at bay in the Western Pacific as Beijing gains control of the South China Sea.

Harris’ visit comes as China is fuming at the deployment to South Korea last month of an anti-missile system that Beijing says damages its national security.

China complains that the radar of the Terminal High Altitude Area Defense, or THAAD, system can see into its territory. The United States says it is intended purely for defense against North Korea.