Japan should consider building a military base on islands disputed with China to counter Beijing's rising assertiveness, a leader of Japan's opposition said Monday on a visit to the United States.

Nobuteru Ishihara, sometimes seen as a future prime minister if his Liberal Democratic Party returns to power, said that Japan should also look more broadly at stepping up defense spending in the face of a rising China.

Asia's two largest economic powers dispute control of a set of uninhabited islands -- known as the Senkaku in Japanese and the Diaoyu in Chinese -- where Japan's arrest last year of a Chinese fishing captain led to a standoff.

Ishihara, secretary general of the conservative opposition party, said that Japan should move "quickly" to put the islands under public control. Tokyo considers most of the area to be privately owned by Japanese citizens.

"Following this change, a port should be developed where fishing boats may take refuge," Ishihara said at the Hudson Institute, a Washington think-tank.

"I further believe that we must seriously begin contemplating the establishment of a permanent post for the Self-Defense Force in this area," he said, referring to officially pacifist Japan's armed forces.

Japan said in 2008 that it reached an agreement with China for joint development of potentially lucrative gas fields near the disputed islands. But the deal has gone nowhere, with China saying its stance has not changed.

Prime Minister Yoshihiko Noda's Democratic Party of Japan -- which swept out the long-ruling Liberal Democrats in a 2009 election -- has mostly sought smooth ties with China, which says its growing military spending is for peaceful purposes.

Noda asked Chinese President Hu Jintao for movement ahead on the 2008 deal during talks last month on the sidelines of an Asia-Pacific summit in Hawaii, although Japanese officials said Hu was non-committal.

But Ishihara said that China has become "assertive, one may even say aggressive," in recent years and pointed to its actions in separate maritime disputes with the Philippines, Vietnam and other Southeast Asian nations.

"Emboldened by its new economic weight and growing military might, China's proclamations of its 'peaceful rise' appear more and more at odds with the emerging reality," Ishihara said.

Ishihara, 54, is the son of Tokyo Governor Shintaro Ishihara, an outspoken nationalist who has often caused controversy by urging Japan to develop nuclear weapons and to be less dependent on its alliance with the United States.

The younger Ishihara distanced himself from his father's positions, calling for close ties with Washington and saying that his party's current leadership has not discussed seeking nuclear weapons.

Ishihara, however, said that Japan should consider boosting its overall defense budget which has long been equivalent to one percent or less of the economy.

Ishihara, leading a delegation from his party, was in Washington partly to ease concerns over the opposition's stance on the Trans-Pacific Partnership, a proposed Pacific Rim trade pact championed by President Barack Obama.

Noda announced last month that Japan would enter talks but has faced strong opposition from farmers worried over foreign competition and threats of a censure motion by the Liberal Democrats, who consider the countryside a key political base.

Ishihara said that discussions on the Trans-Pacific Partnership were "at the starting line" and that Japan's government must do all it can to address public concerns and ensure food security.

"We would like to understand what the US wants to get out of the TPP. If it's an effective tool to establish a free trade zone for the Pacific that benefits both the US and Japan, that would be reason to pursue it," he said.

"But if we cannot identify enough merit for Japan and the US, then maybe we should pursue another way to establish a free trade zone," he said.