Singapore must never let another country influence its domestic debate and politics, Prime Minister Lee Hsien Loong said at the People's Action Party (PAP) convention yesterday.
"While we are friends with many countries, we must never inadvertently fall under foreign control or influence," said PM Lee, who is the PAP's secretary-general.
Such influence can be open or covert, and can divide and weaken Singapore, he said.
PM Lee cited Australia's worries about foreign influence, and America's accusations against Russia of trying to influence its presidential elections last year "quietly and secretly" through social media.
"Can it happen to us? Yes, it can. But we must prevent it from happening," he said.
His comments come three months after Lee Kuan Yew School of Public Policy academic Huang Jing was identified as "an agent of influence of a foreign country" by the Government and expelled.
"When we are put to the test, we will stay united and back the Government. Then we can... defend Singapore's interests as one single, cohesive country," he said.
Right now, Singapore has good relations with the United States and China, and with its immediate neighbours, he said. While relationships will see ups and downs, Singapore's approach is a long-term one: to neither take good relations for granted, nor "get flustered or cower" when relations are down.
PM Lee recounted his September visit to China at the big power's invitation even though it was just before the 19th Party Congress, the largest event in China's political calendar. "Both sides value the relationship, and I discussed with the Chinese leaders new areas of cooperation."
He also visited the US last month, meeting President Donald Trump and his key officials."It is not always easy to be good friends with both the US and China at the same time but, as a small nation, we have to make friends with as many as we can.
"So, we have to work hard... while upholding Singapore's own interests. And I think we have not done too badly," PM Lee added.
Ties with Indonesia and Malaysia are also good, with Singapore investing heavily in both and taking part in major projects with them, he said.
Singapore and Johor are working on a rapid transit link and will sign the agreement for it next month. PM Lee will also play host to Malaysian Prime Minister Najib Razak at a retreat in Singapore next month.
But PM Lee noted that issues will crop up from time to time.
For example, the Pedra Branca case appeared to be settled for good, with the International Court of Justice (ICJ) awarding the rocky outcrop to Singapore in 2008. Almost 10 years later, Malaysia is seeking to reopen the case with the ICJ.
"I am not sure what Malaysia's motive is, but their general election is coming, and maybe that has something to do with it," said PM Lee.
In Indonesia, politicians want to take back control of the flight information region. Singapore manages a flight information region around Changi Airport, including parts of Indonesian airspace.
"Who controls the flight information region is a technical matter of making the best arrangements for air safety. But it has been politicised and made into an issue of sovereignty and national pride... that unfortunately makes the problem much harder to solve," he said.