But both Minister Mentor Lee Kuan Yew and Prime Minister Lee Hsien Loong had the same stark reminder for Singaporeans: Do not take racial harmony for granted.

The harmony Singapore had worked so hard to build could be destroyed by a single flashpoint, like a terrorist attack, they warned.

Speaking at the National Orange Ribbon Celebrations in Bishan, MM Lee told the crowd he would dispense with the speech prepared for him by one of the ministries.

'It's a subject so fundamental, I better speak straight from the heart,' he said.

The Minister Mentor went on to speak passionately for half an hour about the challenges Singapore faced from its earliest days, to build trust between the races.

He said the first important decision the Government made was to break up the old racial enclaves and scatter Singaporeans among neighbours of various races when it resettled them in the public housing estates it built.

Singapore has come a long way since but MM Lee stressed yesterday that it was not yet a nation.

'Over time we have become one community with many races, many cultures... Are we a nation yet? I would not say we are,' he said.

'We are in transition. But we will always progress provided we know where we are and what we have to do to get there.'

To drive home his point, he even took aim at the multi-racial performances at the event.

They were a contrived effort which represented an ideal.

'This is an ideal which we may never completely reach, but because we have this ideal, we will continue to make progress,' he said.

The Minister Mentor said his fear was that the good work could come undone with one terrorist attack.

If a Malay-Muslim Jemaah Islamiah member blew up a bomb in an MRT station and the blast killed more Chinese and Indians than Malays, it would lead to non-Muslims distancing themselves from Muslims out of fear.

That was what happened in Britain after the 2005 London bombings, he said.

Over at another event at Ang Mo Kio GRC, the Prime Minister warned that the terror threat was ever evolving.

He cited last year's attacks in Mumbai and Friday's blasts in Jakarta as examples of terrorists' new tactics. In Jakarta, the suicide bombers actually checked into the hotel they planned to target and assembled the bomb in their hotel room.

'So new tactics, new approaches, new ways of doing evil, bad deeds and we must be prepared for them to try this sort of thing on us, and we must be prepared to resist it and prevent it.

'First, prevent it from happening, and if despite all our efforts it still happens, prevent it from damaging our society, fracturing our racial harmony, pulling us apart, making us fight each other and destroy the whole country,' he said.

Noting that it has been 40 years since the last racial riots here, he said: 'Sometimes if we don't remind ourselves, we may think that this (peace) is a natural state of affairs which has happened by itself and which will continue by itself.

'But it is not like that. It is something special in the world.'

Over at Bishan, MM Lee unveiled a 9-feet tall star-shaped structure containing 150,000 little paper stars, each one with a Singaporean's written pledge to live in harmony.

An inscription on the structure carried MM Lee's own pledge: 'Harmony is a base for stability, growth and progress.'

Working towards an ideal

'This is an ideal which we may never completely reach, but because we have this ideal, we will continue to make progress.'

MM LEE on how the multi-racial performances at the event were a contrived effort which represented an ideal

Staying vigilant

'Sometimes if we don't remind ourselves, we may think that this (peace) is a natural state of affairs which has happened by itself and which will continue by itself. But it is not like that. It is something special in the world.'

PM LEE, at another event yesterday