Prime Minister Kevin Rudd headed home last night after a six-day visit to China, South Korea and Singapore.

Mr Rudd jetted into Singapore yesterday morning, where his first duty was to visit the Kranji War Cemetery, where more than 2500 Australians are buried or commemorated.

Mr Rudd fitted in meetings with Singapore's Prime Minister Lee Hsien Loong, senior minister Goh Chok Tong and former prime minister Lee Kuan Yew during his 12 hours in the city state.

The highlight was the signing of a defence pact between the two allies, aimed at extending the strength, depth and breadth of their security cooperation.

Mr Lee said defence was a key pillar of cooperation between the two countries.

''We have been partners in the five-power defence arrangements since 1971 and our armed forces have a well-established working relationship honed through many joint exercises and training courses.''

Later this year, Singapore will send a 20-strong medical team to work with Australian troops in Oruzgan province in southern Afghanistan.

Mr Rudd said Australia's defence ties with Singapore were important to both countries, as well as the region.

''[It's] important in terms of the wider stability, strategically, of South-East Asia,'' he said.

Yesterday afternoon, Mr Rudd delivered the 29th Singapore Lecture, where he focused on the growing global importance of the Asia-Pacific region this century.

Mr Rudd, a renowned Sinophile, singled out the rise of China as one of the key defining developments of the 21st century.

''The rise of China ... represents the great unfolding drama of this new century,'' he said.

''Will China democratise? How will China respond to climate change? How will China deal with crises in the global economic and financial systems? How will China respond domestically to the global information revolution?''

Mr Rudd said countries like Singapore and Australia could have a direct influence on how China responded to these challenges.

''How China responds to these forces will radically shape the future course of our country,'' he said.

''Australia's future will also depend on our ability to engage constructively and effectively with the countries of the Asia-Pacific. That is why I am committed to making Australia the most Asia-literate country in the collective West.

''By investing in Asian languages and cultural education in Australia's schools, my vision is for the next generation of Australians... to develop language skills which open their region to them.''

Mr Rudd returned to Australia in a commanding political position, with Monday's Newspoll showing Labor maintaining a two-party-preferred vote of 57per cent against the Coalition's 43per cent.

Mr Rudd's approval rating stayed static.

But Opposition Leader Brendan Nelson's satisfaction rating dropped from 33 to 31per cent, while his dissatisfaction rating climbed from 42 to 48per cent. AAP