(CNN) -- China isn't a military threat to its neighbors, the nation's defense minister told his counterparts at a security forum of the Association of Southeast Asian Nations.

U.S. Defense Secretary Robert Gates tread lightly at the same gathering Tuesday in Vietnam, referring to territorial disputes and aggressiveness, but avoiding direct criticism of China.

"The United States does not take sides on competing territorial claims, such as those in the South China Sea," he said. "Competing claims should be settled peacefully, without force or coercion, through collaborative diplomatic processes, and in keeping with customary international law."

Beijing says most of the South China Sea belongs to China, disputing neighboring countries' claims. The clash over territorial waters and islands -- and the natural resources that go with them -- is a flash point in the Asia-Pacific region.

"China pursues a defense policy that is defensive in nature," Defense Minister Liang Guanglie said. "China's defense development is not aimed to challenge or threaten anyone, but to ensure its security and promote international and regional peace and stability."

Liang's statements came on the heels of a diplomatic clash with Japan over the arrest of a Chinese fishing captain in September. He was detained off the disputed Diaoyu Islands, in the East China Sea, touching off a battle that escalated into diplomatic threats by Beijing, the suspension of diplomatic talks and canceled trips between the nations. In Japan, the islands are known as the Senkaku.

Japan late last month freed the fishing captain, who returned to a hero's welcome in China.

In the aftermath of that clash, China's and Japan's top leaders signaled a thaw in relations by meeting on the sidelines of the Asia-Europe Meeting last week in Belgium.

China and the United States have done likewise this week at ASEAN in Hanoi, Vietnam.

The U.S. defense secretary also has accepted an invitation to visit Beijing next year, to further rebuild military ties.

Beijing had cut off military dialog with the United States after the Obama administration announced a planned sale of arms to Taiwan earlier this year.

ASEAN is a political and economic organization consisting of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam. The talks in Vietnam also include Australia, China, India, Japan, New Zealand, Russia, South Korea and the United States.