US President Barack Obama assured ally Japan on Thursday that Washington was committed to its defense, including of disputed islands, but denied he had drawn any new "red line."

On the start of a four-nation tour, Obama is being treated to a display of pomp and ceremony meant to show that the US-Japan alliance, the main pillar of US security strategy in Asia, is solid.

The US doesn't take a position on final sovereignty determinations with respect to islands disputed by Japan and China, the president told a joint press briefing with Japanese Prime Minister Shinzo Abe on Thursday in Tokyo.

"But historically they have been administered by Japan and we do not believe that they should be subject to change unilaterally and what is a consistent part of the alliance is that the treaty covers all territories administered by Japan," Obama said.

But he said, "In our discussions, I emphasized with Prime Minister Abe the importance of resolving this issue peacefully."

Responding to Obama's speech, China on Thursday restated its firm opposition to putting the Diaoyu Islands within the scope of the US-Japan Treaty of Mutual Cooperation and Security.

"The so-called US-Japan security treaty is a product of the Cold War era and it cannot be aimed at a third party and ought not to harm China's territorial sovereignty," China's foreign ministry spokesman Qin Gang told reporters at a regular press conference.

"No matter what anyone says or does, the fact that the Diaoyu Islands are an inherent part of Chinese territory wouldn't change."

Meanwhile, a Chinese defense ministry spokesman said Thursday that China's army absolutely has the ability to protect the islands, which are part of Chinese territory.

When remarking on Japan's breaking ground on a radar station on Yonaguni Island, some 150 kilometers from China's Diaoyu Islands, the spokesman said, "China has been closely following Japan's recent military moves and the Chinese military will continue its patrols and military training in the areas concerned."

After Obama's vow that the islands are subject to the mutual defense treaty between Washington and Tokyo, Seoul on Thursday said it considers its disputed islets of Dokdo (called Takeshima in Japanese) covered by a security treaty between South Korea and the US.

"Our government's stance is that Dokdo is a territory under South Korea's administrative control as stipulated in the South Korea-US Mutual Defense Treaty," foreign ministry spokesman Cho Tai-young said in a briefing.

It was unclear whether Obama would discuss Dokdo with South Korea when he visits the country later this week, the spokesman said.

Agencies - Global Times