SHANGHAI (Kyodo) Japan should strengthen relations with China because ties with the United States have been strained over the relocation of the U.S. Futenma base in Okinawa, Kenji Yamaoka, Diet affairs chief of the ruling Democratic Party of Japan, said Monday.

"Japan-U.S. ties are strained. It is a realistic approach to first strengthen Japan-China ties and then resolve the problems with the United States," Yamaoka said at a symposium in Shanghai.

He also said Ichiro Ozawa, secretary general of the DPJ, and Chinese President Hu Jintao agreed during a meeting Thursday in Beijing that trilateral relations should be equally balanced like an equilateral triangle.

Japanese-U.S. ties have soured recently after the Hatoyama administration started to re-examine the relocation of the Futenma airfield, which had already been agreed to in an agreement signed in 2006.

"The American government should come up with a new global strategy," Yamaoka said, adding that if the current framework established after the Cold War continues, there will be a "difficult period" in the long run.