BEIJING/WASHINGTON – China has unveiled plans to build more aircraft carriers after commissioning its first last year, as the country extends its influence amid territorial disputes with neighbors including Japan and Vietnam.

Future aircraft carriers will carry more fighter jets than the Liaoning, Rear Adm. Song Xue told foreign military attaches Tuesday in Beijing, according to the state-run Xinhua news agency. The Liaoning carrier was built around a Soviet-era hull and began sea trials last year.

The remarks signal that the People’s Liberation Army will push ahead with a modernization plan under which defense spending has more than doubled since 2006. China has become more assertive in pressing sovereignty claims against Japan as well as Vietnam and the Philippines in the South China Sea.

“This only adds publicly to what many believed to be the case: that the Liaoning is a training or ‘starter’ carrier and eventually China would build larger and more capable ones,” said Taylor Fravel, a professor at the Massachusetts Institute of Technology who focuses on China’s relations with its neighbors. “It suggests that today’s PLA is much more confident than in the past regarding its willingness to talk about future military programs.”

The carrier announcement came as Gen. Martin Dempsey, the chairman of the U.S. Joint Chiefs of Staff, visited China. He and Chinese counterpart Fang Fenghui said Monday that they want to expand military ties.

At the same time, tensions between China and Japan have escalated over isles in the East China Sea that are claimed by both sides.

“Relations between China and Japan are at their worst since diplomatic ties were established in 1972,” Rumi Aoyama, a professor of Chinese studies at Tokyo’s Waseda University said Tuesday. “At this point, it’s about maintaining lines of communication to make sure things don’t get worse.”

China has also pressed its claims in the South China Sea. Last month, a Chinese ship fired on a Vietnamese fishing vessel in an area of the sea claimed by both sides. Chinese and Philippine vessels squared off early last year over claims to a reef known as the Scarborough Shoal.

Zhang Zheng, the Liaoning’s captain, told foreign attaches that the carrier’s crew had mastered the ship’s weapons systems, Xinhua reported.

Song, the rear admiral, said that the J-15 fighter aircraft needed more trials before becoming operational on the carrier, according to the report.