Malcolm Turnbull has revealed that he encouraged Donald Trump to “take the lead” and develop 5G networks in cooperation with allies, including Australia, to hold out “ferocious competition” from China and to safeguard networks against cyber-attacks.

In a speech in New York overnight, the former prime minister said that in response to concerns China was stealing a technological march he had urged the US president to “ensure that we had at least one viable and secure 5G vendor from the United States and/or its Five Eyes partners”.

“It is, frankly, absurd that in this, arguably the most important enabling technology of our time, the United States and its closest allies like Australia are not leading players,” Turnbull said.

He had been pleased to see Trump announce this month that “that 5G is now a priority for his government to ensure US companies got up to speed”.

In the past countries in the west had been able to keep “high-risk” vendors from providing core equipment or capabilities, leaving them supplying services at the edge of the network rather than its core.

“But with 5G we have had to recognise that core/edge distinction no longer exists,” he said. “Right now a mobile network operator, like AT&T or Verizon, has just four full-service vendors from which to choose for its 5G network equipment. Two are from China (Huawei and ZTE) and two are from Scandinavia (Nokia and and Ericsson).

“Ferocious competition from the Chinese vendors on price and an absence of mind in Washington and other Five Eyes capitals has got us to the position where, when network security is more important than ever, there is not one 5G vendor from the United States or its Five Eyes allies.

“Indeed, there isn’t one from Japan, either, and the closest new prospect is Samsung of Korea.”

Turnbull revisited one of the last decisions he took as prime minister before being deposed by colleagues last August. He said cabinet’s national security committee had banned high-risk vendors from Australian 5G networks. That decision was taken amid the leadership tensions that culminated in the conservative-led move against him.

The exclusion angered the Chinese government. “The Australian government has made the wrong decision and it will have a negative impact to the business interests of China and Australia companies,” its commerce ministry said.

Turnbull said the committee’s definition of high risk was firms that “could be subject to directions from foreign intelligence services to act contrary to our national security”.

“The Chinese National Intelligence Law of 2017 makes it abundantly clear that Huawei and ZTE are subject to such obligations and accordingly they were excluded from the 5G rollout in Australia,” he said. Australia had been the first nation to impose a ban and “our decision was not taken lightly”.

He had asked Australia’s intelligence agencies to investigate how the risks could be mitigated to allow participation from Chinese companies. “After that very intense research and investigation, their unequivocal advice was that mitigation was not effectively possible.

“The decision was not a judgment on present or near-term threats but, as is more often the case, a long-term prudent hedge. Remember, threat is the combination of capability and intent. The former can take years or even decades to put in place, intent, on the other hand, can change in a heartbeat.”

Turnbull said he had formed a view that a nation like Australia “surrounded by friends, particularly well-armed ones, would be unwise to allow that neighbourly warmth to lead it to neglect its own defences”.

In an Anzac Day speech to the Australian American Veterans Scholarship Fund in New York, Turnbull did not address rising tensions in the South China Sea or the rapid build-up of naval power in the Asia-Pacific region but zeroed in on cyber-threats.

“Fleets and armies are tangible – and menacing – examples of coercive power but their usefulness is largely as a deterrent,” Turnbull said. “Once deployed in combat, the consequences are costly and hard to control or calibrate.

“However, cyber-warfare is very different. There the cost of interference is much lower, and state actors do not by any means have the arena to themselves.

“It is very hard to deny the origin of a missile, but cyber-attacks are notoriously hard to attribute – and that is assuming you know it is going on in the first place.

“In other words the cybersphere offers opponents the ability to inflict damage at relatively low cost to themselves, with a high degree of deniability and relatively little prospect of effective retaliation.”