"The International Trading System is also under stress, with the Doha Round struggling to make progress. If another test comes, ASEAN must not be found wanting again," Mr Lee noted. But he welcomed the stable relation in the regional, especially among key players, China, India and Japan.
"Tensions in potential flashpoints are also easing,' he pointed out. Cross-strait relations are on an upturn following the election of Taiwanese President Ma Ying-jeou, while North Korea's submission of its nuclear programme declaration has led to the resumption of the Six-Party Talks after a hiatus of nine months, he noted.
"While we work to strengthen ASEAN, we should also not lose sight of our place in the evolving regional and international landscape," he urged ASEAN member countries.
He also called on the 10-nation Association of South East Asian Nations (ASEAN), not to take its continued relevance for granted.
"If our efforts to achieve faster and deeper integration falter, ASEAN may well be sidelined," said Mr Lee.
The meetings including bilateral sessions with China, South Korea, Japan, India, Australia, New Zealand, Canada, Russia, the United States and European Union, ends of 24 July.