The summit is scheduled to be held in Kuala Lumpur in December among the 10 member states of the Association of Southeast Asian Nations (Asean) as well as China, Japan, South Korea, India, Australia, New Zealand.
The original idea was to turn the annual leaders' meeting between Asean members and China, Japan and South Korea - under the existing "Asean plus three" process - into an East Asian Summit as part of ambitious plan to create an East Asian community backed by a regionwide free trade area.
But Singapore, Japan and Indonesia particularly objected, fearing it would alienate the United States and lead to possible Chinese dominance. They lobbied for the expansion of the forum to cover Australia, New Zealand and India.
Still, China and some of the Asean states remain hopeful that the "Asean plus three" vehicle is the umbrella forum to forge an East Asian community.
As the upcoming summit has expanded to cover countries beyond the geographic notion of East Asia, the question has arisen whether the United States - which is on the other side of the Pacific - should be a participant.
"It's a question we get all the time: what is our policy on the East Asia summit? Quite frankly, we haven't determined a policy because the East Asia summit, if you really look at it, is a black box," said deputy US assistant secretary of state Eric John.
"Nobody knows what the East Asia summit is other than leaders coming together," he told a recent Congressional hearing when legislators asked why the United States, being the Asia-Pacific region's largest economic and military power, was not invited to join the forum.
One key unanswered question is whether the forum would tackle political, economic or security issues, John said.
"But once the forum begins to take form, we will study how we can engage. Until that time, I would hesitate to push for an invitation to an organisation we don't know what it does," he explained.
The three prerequisites for participation in the East Asian summit are member countries should have substantial relations with Asean, be an Asean dialogue Partner and accede to a non-aggression treaty known as the Treaty of Amity and Co-operation.
While other big powers Russia, China and India have become signatories to underscore security commitment to the region, the United States said it has no current plans to sign up.
Even so, Russia's application to join the first summit has been rejected on the basis that Moscow does not have substantial relations with the region.
But when Asean accepted Russia as a dialogue partner several years ago, it was due to its strategic importance and not relations with the region, some experts said, raising doubts over the basis for membership of the summit and the direction it would take.
It is very unlikely that the summit would lay the groundwork for an East Asian community, one Southeast Asian diplomat said, adding that such a mammoth task cannot be undertaken by a forum which has no implementation mechanism.