U.S. President Barack Obama joins other East Asian leaders Saturday at an ASEAN summit for the first time ever.

The move is widely seen as a landmark step to proclaim the United States' high-profile return to the "once-omitted" region, a region it has largely disregarded for decades.

In the 1990s, former Malaysian Prime Minister Datuk Seri Mahathir proposed to establish an East Asian economic forum. The idea was strongly opposed by Washington over concerns that such a measure could jeopardize its interests and challenge its hegemony.

Though the United States set up a dialogue relationship with the Association Southeast Asian Nations (ASEAN) in as early as the 1970s, it was not until in July 2009 did Washington finally sign the Treaty of Amity and Cooperation in Southeast Asia.

For a long period, Washington saw the East Asia Summit as a redundant mechanism whose goal and significance were unclear.

Then surprisingly, the United States made a U-turn in its Asia strategy with Secretary of State Hillary Clinton declaring a policy shift.

The top U.S. diplomat said prior to the APEC summit meeting in Hawaii last week that "there are challenges facing the Asia-Pacific right now that demand America's leadership" and the 21st century will be "America's Pacific century."

On top of that, Washington took a series of steps to promote its pivot strategy by declaring a high-profile "return" to Asia.

The superpower expanded military deployment to Australia and was actively involved in East Asian cooperation mechanisms while attempting to court several East Asian countries and interfere in long-standing disputes between countries in the region.

It clarified its nature as an Asia-Pacific power to seek "America's Pacific century" and secure the Asia-Pacific's security and prosperity.

The U.S. move has fueled strong suspicions from the region. Many countries wonder what kind of "leadership" America aspires to assume in the future.

The hard fact is that the Pacific Ocean belongs to all countries sharing its shores, not just the United States.

By claiming a return, Washington is confronted with questions it is hardly able to answer: How can the United States earn Asian countries' trust? How will it help maintain regional stability and promote common prosperity? And what steps it will take to get along with the rising regional power China?

Actually, China as well as other Asian nations never considered the United Sates had left the Asia Pacific and had never tried to squeeze it out of the region. They are also unlikely to approve of the U.S. attempt to impose its values on them or the so-called "leadership" it aspires to exercise in Asia.

What they need right now is a reliable partner, not a country that yearns for leadership and intends to act as an arbitrator.

After years of cooperative endeavors with the rest of the world, southeast Asia has undergone significant changes. Mutually beneficial cooperation and peaceful development have become the region's main theme.

If the United States sticks to its Cold War mentality and continues to engage with Asian nations in a self-assertive way, it is doomed to incur repulsion in the region.

It is also called upon to guard against sparking disputes and encroaching on others' interests. Otherwise, the region's stability and prosperity will become an impossible dream.