Japan should maintain its spending on hosting U.S. military bases and personnel in the country and help ensure regional security, said Andrew Shapiro, U.S. assistant secretary of state for political-military affairs and a senior official involved in bilateral negotiations.

Over the last decade, Japan has been cutting the budget for "host nation support," which covers such costs as utility charges at bases and salaries paid for Japanese workers.

The government of Prime Minister Naoto Kan is widely seen as exploring the possibility of reducing the spending further as part of efforts to restore the nation's fiscal health.

"We are asking the Japanese people to contribute and to invest in the U.S.-Japan alliance," Shapiro said during an interview Friday, while visiting Tokyo for negotiations with Japanese officials.

Shapiro cited "challenges" and "threats" in East Asia. "The role that the U.S. military plays in Japan and the region cannot be understated," he said.

Japan has reduced host nation support over the last decade or so, and the related budget for the current fiscal year is about ¥188 billion.

During the two days of talks, which ended Friday, U.S. and Japanese officials mainly discussed the possible revision of a bilateral treaty that gives legal backing to the Japanese government for a large part of such spending. The treaty expires next March.

The talks "got off to a very good start," Shapiro said of the meeting, expressing his hope that the negotiations will be concluded "as quickly (and) expeditiously as possible."

A senior Japanese official said, however, the negotiations will be tough and last until around yearend.