PHUKET, Thailand – U.S. Secretary of State Hillary Clinton signed a friendship treaty with Southeast Asia on Wednesday, underlining Washington's renewed focus on a region that has increasingly come under China's influence.

Other countries including China have acceded to the Treaty on Amity and Cooperation, a document that underpins the 10-member Association of South East Asian Nations (ASEAN). It commits signatories to the peaceful settlement of disputes and non-interference in domestic affairs.

The United States is back in Southeast Asia, Clinton declared at a news conference on the Thai island of Phuket before she signed the treaty and held talks with ASEAN foreign ministers.

President Obama and I believe this region is vital to global progress, peace and prosperity and we are fully engaged with our ASEAN partners on the wide range of challenges confronting us.

Some analysts say Washington's enhanced interest in Southeast Asia could assuage some concerns in the region about China's growing clout, especially over Beijing's projection of naval power in the South China Sea.

Clinton's meetings on Wednesday precede Asia's biggest annual security gathering, the ASEAN Regional Forum (ARF), which takes place on Thursday and where North Korea's nuclear program will be high on the agenda.

U.S. officials had said Clinton wanted to stress Washington's interest in ASEAN, a region home to 570 million people and with combined economic output of $1.1 trillion.

Washington routinely sent lower level officials to ASEAN meetings under former President George W. Bush.

I understand they really, genuinely desire to expand and deepen cooperation and the relationship. We welcome that shift, ASEAN Secretary-General Surin Pitsuwan told Reuters.

Clinton is also likely to discuss Myanmar with ASEAN, whose soft approach to the military junta is a source of friction with the West. Even though it has now signed the ASEAN treaty, Washington is unlikely to hold back condemning the human rights record of Myanmar, also known as Burma.

Burma is moving in the opposite direction of the other ASEAN countries, we have been very clear the U.S. would like to see changes in the behavior of the regime in Burma and we think other countries in the region feel the same, Clinton said.

CHINA LOOMS LARGE

China's growing economic influence and huge market make it an important participant in ASEAN meetings, but tensions persist, especially over competing claims in the South China Sea, the shortest route between the Pacific and Indian Oceans.

Last year, trade between the United States and Southeast Asia was $178 billion, while cumulative American investment in the region is around $100 billion. China-ASEAN bilateral trade is worth $231.1 billion, with two-way investment around $60 billion.

Asked in Bangkok on Wednesday if Washington was trying to balance China's rise, Clinton said: ... The more we involve China in the work we are doing and in organizations like ASEAN, the more opportunities we have to create a positive framework.

Now, I know 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. But what we hope is that we all can work together and that China remains focused on raising the economic well-being of their people and competing in the market place.

The Washington-based Center for Strategic & International Studies (CSIS) in a report this month said Southeast Asia welcomed increased Chinese engagement but remained wary of the implications, particularly in military affairs.

If there was a period in which the region succumbed to a Chinese 'charm offensive', that period is clearly over, said the report, based on extensive visits to the region late last year.

While nations appreciated the benefits offered by China's rise ... regional interlocutors were often blunt about the challenges to national interests posed by China, in the South China Sea in particular, but also in the overall regional balance of power given China's military modernization.

(Additional reporting by Martin Petty, Ben Blanchard and Kittipong Soonprasert; Editing by Jeremy Laurence)

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