By Jonathan Head
BBC News, Singapore
This year the Association of South East Asian Nations (Asean) is marking its 40th anniversary, and the 10-country regional group has much to look back on with pride.
Among its members are countries which have transformed themselves from impoverished agrarian societies into some of the world's most dynamic economies.
The Asean summit is being overshadowed by a rift over Burma
The citizens of Singapore, which is hosting this week's summit of the group's leaders, enjoy one of the highest living standards anywhere.
Potential conflicts within the region have been successfully defused. One of the association's greatest achievements was helping end the long civil war in Cambodia, paving the way for the communist countries of Indochina to join Asean.
But all of this is being overshadowed now by the fateful decision 10 years ago to admit Burma as a member.
The brutal suppression by Burma's military rulers of anti-government protests in September has outraged world opinion.
But it has also cast an unfavourable light on Asean's hallowed principle of non-interference in its members' internal affairs.
'Veil of respectability'
Earlier this month the US Senate passed a resolution calling on Asean to suspend or expel Burma.
Other governments have been pushing Asean to find other ways to put pressure on the generals who run Burma, and for whom membership in the group has in the past offered a rare veil of respectability.
Privately some member governments now acknowledge that allowing Burma into the association was a blunder - but they are not prepared to say this openly.
Asean still likes to refer to itself as a family, which deals with its own problems behind closed doors.
So why did such a successful regional grouping feel the need to have Burma as a member?
"A decade ago South East Asia was a different place," says Thitinan Pongsudhirak, a political scientist at Chulalongkorn University in Bangkok.
"Relations with China were not amicable - and there was a fear that if Burma was left out it would fall into China's orbit."
There were other factors.
At the time the decision was made, right before the great Asian financial crisis of 1997, South East Asia was riding high, its economies hailed as miracle "tiger" economies, as yet untroubled by competition from China.
There was enormous self-confidence - and a commonly expressed belief in so-called "Asian values" that stressed national discipline and economic growth before human rights and personal liberty.
The Asean countries were convinced that flattering Burma's military government with membership would get better results than the western policy of sanctions.
The prospect of entering Burma's untapped markets as it grew, and getting access to its wealth of natural resources was also a powerful attraction.
There is no doubt that these factors still influence policy towards Burma.
About 70km north of Bangkok is Wang Noi power station, one of Thailand's most modern and efficient, that provides much of the capital's electricity needs.
It is also fuelled mainly by natural gas piped in directly from Burma.
In fact Burmese gas now accounts for around 20% of all Thailand's electricity, earning the military government around $2bn (£1bn) a year, and making Thailand its largest trading partner.
It would be difficult for Thailand to find an alternative energy source even if it wanted to.
But the embarrassment of having such a pariah state as a member is starting to outweigh these advantages.
"We need them to move on and accept change, because their problems are a distraction from our goal of building a more integrated Asean," said Ong Keng Yong, the association's secretary general.
The use of force against unarmed protestors, and the subsequent mass arrests, are particularly embarrassing as Asean leaders prepared to sign their first ever charter, which enshrined respect for human rights as a core value of the association.
Some banks in Singapore are now believed to be restricting access to financial services to some of the businesses closest to the ruling junta in Burma.
There has been no change in regulations to make them do this - it is assumed they may be worried instead about their reputations in the rest of the world.
And there are voices within Asean now arguing that it would be better to suspend Burma's membership, not so much as a punishment, but to allow the other nine members to move on.
One such voice is Barry Desker, Dean of the Institute of Defence and Strategic Studies in Singapore.
Burma's military violently ended monk-led anti-government protests
"The question I have posed is: Can Asean afford to have a member which has failed to ensure the wellbeing of its people, not just recently but since it joined? I am arguing for suspension not because I think it would improve conditions on the ground in Myanmar [Burma], but because of the effect is having on Asean."
But for an organisation which prizes harmony above all else, such a move is seen as far too provocative.
Besides, Asean can make decisions only through a consensus of all 10 members. Burma would have to agree to be suspended for that to happen.
There is a deep-rooted belief here that confronting the generals with punitive measures might simply drive them further into isolation.
"We are not vital to them," Singapore's Prime Minister Lee Hsien Loong told the BBC.
"Their imperative is to survive as a regime. Supposing we expel Myanmar from Asean, what difference does it make? How will it improve the situation, or enhance our influence?"
Any pressure on Burma at this summit will be exerted privately, on the sidelines of official meetings.
With the prime ministers of China, India and Japan also present, there is plenty of scope for a strong message to be conveyed to the Burmese delegation, especially given the widely-held fears that the military government may be driving the country towards economic collapse.
But whether that message will be heard, any more than the censure and sanctions emanating from the EU and the US, is anyone's guess.