HONG KONG — The June 18 announcement of the Beijing-Tokyo agreement to jointly develop gas fields in the disputed waters of the East China Sea should help ease tensions between the two countries as they try to forge a new, forward-looking cooperative relationship, but it may cause internal difficulties for China.

The accord was difficult to reach because of overlapping territorial claims, and the two countries describe the agreement differently. In Japan, two Cabinet members, Foreign Minister Masahiko Komura and Akira Amari, minister of economy, trade and industry, announced the news at a news conference, with Komura declaring that "Japan and China have reached a political agreement over cooperation in the East China Sea."

In Beijing, the government adopted a much lower profile. The news was announced by a more junior official, Jiang Yu, spokeswoman for the Foreign Ministry, who described the accord as a "principled consensus on the East China Sea issue."