Launched in 1966, the Eastern Sun was an English-language daily run by Mr Aw Kow, who started it with HK$6 million he borrowed from a Chinese communist news agency based in Hong Kong.
Mr Aw was the son of one of the Tiger Balm brothers.
The newspaper faced financial problems soon after it began operations.
Communist officials injected another HK$1.2 million, but with an added condition that Mr Aw should appoint their representative as an adviser to the newspaper. Mr Aw agreed.
The newspaper shut down in 1971 after its arrangement with the communist agency was exposed by the Government.
Mr Shanmugam said Eastern Sun was a case of black ops.
"It was an attempt by communist China to capture and manipulate the local media, ultimately, to influence public opinion and create political situations favourable to their own interests."
"Communists even allowed the newspaper to take an anti-communist line. As former prime minister Lee Kuan Yew pointed out, this reflected their long-term approach and patience, so that ultimately they have an institution of influence."
An English-language newspaper started in July 1970, it had editorials that played up issues like national service, which it wanted done away with, said Mr Shanmugam.
Among its shareholders was Hong Kong businesswoman Aw Sian, who told then Prime Minister Lee Kuan Yew that she gave $500,000 of her own money for the initial financing of the paper.
But she said she had no knowledge of its financial standing, he recounted.
"Mr Lee asked her, if you don't know how it is doing, how come you're sending this money if it was yours? You're a veteran businessperson."
The Chase Manhattan Bank's Singapore branch also gave overdraft facilities to the Herald. But the chairman of the American bank told Mr Lee in May 1971 that Chase had a standing rule not to lend money to newspapers, said Mr Shanmugam.
The newspaper was shut down that same month.
"Singapore's intelligence agencies concluded that American intelligence had a significant role in these operations, and that this was (a) foreign influence operation."
He added: "The motive was to create a weapon that would shape public opinion as a pressure point, and also to create an outlet that would be anti-communist against the Soviets and against communist activities in this region.
"So you can see equal opportunity, it's not just one country or another."
Lim Min Zhang