Days before China and the United States were scheduled to hold their first Strategic and Economic Dialogue in Washington, Secretary of State Hillary Clinton turned up in Phuket, Thailand for the annual ministerial meeting of the Association of Southeast Asian Nations (Asean), something that her predecessor, Condoleeza Rice, used to skip.

"The United States is back in Southeast Asia,” she declared at a press conference. “President Obama and I believe that this region is vital to global progress, peace and prosperity.

During the Bush administration, Washington used to be quite relaxed about China making inroads in various parts of the world, including Southeast Asia, Africa and even Latin America, America’s backyard. Not any more.

In May, Mrs. Clinton, while meeting with foreign service officers at the State Department, said candidly that Iran and China had made “quite disturbing” gains in Latin America. “We are competing for attention and relationships with at least the Russians, the Chinese, the Iranians,” she said, and cautioned that it was not in America’s interest “to turn our backs on countries in our own hemisphere.”

And so, the Obama administration has decided to compete for influence and attention around the world with other countries, particularly China.

American efforts in Southeast Asia are particularly noteworthy. While Clinton was in Thailand, she signed the 1976 Treaty of Amity and Cooperation in Southeast Asia (TAC), which the United States had in the past refused to sign. In 2003, China became was the first country outside the region to accede to the document, followed quickly by India.

American delay in signing the treaty means that the United States was preceded by Japan, Pakistan, South Korea, Russia, New Zealand, Mongolia, Australia, the European Union, East Timor, Bangladesh, Sri Lanka and North Korea. In fact, with Washington’s decision to join the treaty, Canada is now the only country to participate in the Asean Regional Forum that has not signed on.

The United States had refused to sign the treaty for fear that its emphasis on non-interference in domestic affairs would constrain American freedom of action to impose sanctions on other countries, such as Burma, and that it might undermine alliances with Japan, South Korea and Australia.

However, by now, all these American allies have signed the treaty, reflecting the importance they assigned to Southeast Asia, although they had made it clear before signing that the treaty would not affect their obligations under other international agreements.

Accession to the treaty is a prerequisite to membership in the East Asian Summit. Thus, the United States is now poised to further deepen its involvement in the region by applying to join that body as well. China is known to be cool to the idea of American participation in the East Asian Summit.

While in Thailand Mrs. Clinton spoke at a town hall meeting and was asked if the United States was paying more attention to the region “because you want to balance China.” She pretty much confirmed it by responding that “we all want China’s remarkable rise to be a peaceful one,” adding that “a lot of China’s neighbors have expressed concerns, so we want to strengthen our relationships with a lot of the countries that are in East and Southeast Asia.”

For its part, the 10-nation Asean body formally welcomed “the renewed interest of the Obama Administration in Southeast Asia.” Surin Pitsuwan, Asean’s secretary general, said accession to the treaty “represents in concrete terms a shift of strategy on the part of the new U.S. administration towards Asean.

As if to underline American interest in the region, Clinton also held an unprecedented ministerial meeting with the countries of the Lower Mekong—Cambodia, Laos, Vietnam and Thailand—to discuss issues “related to water, health, and the environment.

Such a meeting was diplomatically significant because these small countries, which have little political heft, are concerned about the impact on them of a series of eight dams that China is building along the river, which originates in Tibet. By holding this meeting, Washington was injecting itself into the situation and signaling that it had interests in this geopolitically important sub-region.

China has taken note of the renewed American interest in Southeast Asia. The official press agency, Xinhua, reported “deepening U.S. engagement in the region after years of negligence” and termed U.S. accession to the amity treaty “a widely-watched move that could have profound implications for the future of Southeast Asia, as well as the Asia-Pacific region at large.” The game is on.