By Rob Watson BBC Defence and Security correspondent, Singapore

Rumsfeld called on China, Russia and North Korea to be more open

Speaking at an annual security conference in Singapore, he pledged continued US engagement in the region.

Last year, Mr Rumsfeld stole the headlines for his outspoken criticism of China's secretive military build-up.

This year he has been far more diplomatic, speaking optimistically of US relations with Russia and China.

However he again questioned China's lack of transparency over its military spending and what he said were Russia's attempts to restrict the freedom of its smaller neighbours.

Their future behaviour, he said, along with the challenges posed by North Korea and the threat of Islamic extremism, would in large part determine Asia's future.

Most strikingly, Mr Rumsfeld repeatedly stressed continuing US military and economic interests in the region - a point that will not be lost in a part of the world where countries are constantly weighing the meaning of the rise of China and India for future security relationships.