In August 1989, as Hun Manet was nearing his 12th birthday, his father was in Paris, piquing the international media’s attention as the gangly young prime minister leading the Vietnam-backed Phnom Penh government in talks to end Cambodia’s bloody civil war.

Cambodia’s Hun Sen: In Phnom Penh, Vietnam’s ‘puppet’ finds his voice, proclaimed a headline in the New York Times, which noted the ex-Khmer Rouge guerilla’s growing self-confidence as he traded barbs with then-Prince Norodom Sihanouk, head of the resistance and 29 years his senior.

Hun Sen, remarked the newspaper, had grown from a “tongue tied” 27-year-old to an “articulate and unintimidated” prime minister of 38, who, for young Cambodians who had little memory of Sihanouk’s reign, “represents modernity”.

Today, as the premier looks to extend his rule at the 2018 national election, the task of representing modernity for his Cambodian People’s Party has fallen to his children.

Over the past year, it has been Hun Manet who has been tasked with following in his father’s footsteps abroad and cultivating support on foreign turf, long the domain of the opposition.

Now 39 years old, the scion has found the going tough.

Beset by protesters in the US and Australia and entangled in a legal case lodged in California, Manet has been confronted by the inherent tension in his role – one that seeks to play down the misdeeds of his father, while still serving as his representative.

Long shadowed by rumours he is being groomed for leadership, Manet will increasingly have to confront the “problem of the anointed successor” as he continues his career, said Caroline Hughes, a Cambodia expert at Bradford University in the UK.

His rise from an 18-year-old student at the US’s elite West Point military academy to top echelons of the Royal Cambodian Armed Forces is inextricably linked to his father, whose legacy he must embrace, Hughes argues.

However, those same ties give him little room to assert himself or ability to manoeuvre when confronting criticism.

“Politically, it can be an impossible role,” she said in a recent interview. “You would be ruining your chances if you did anything that wasn’t totally deferential, but on the other hand, who wants a leader who’s totally deferential?”

In television interviews with international outlets, Manet, a lieutenant general in Cambodia’s military, deflects critical questions on human rights abuses and corruption and, speaking softly, pushes a ruling Cambodian People’s Party line, emphasising the country’s peace, stability and development under his father’s rule.

But upon his return from Australia last month, Manet spoke frankly to local media and vented his exasperation at his treatment abroad.

“What was the benefit?” Manet asked of the protests and “hate” he encountered in Australia, which he, like his father, blamed on the opposition Cambodia National Rescue Party.

“I just came to hear about [what Cambodian-Australians think about] our country. So why are they looking down on me, causing divisions and conflicts? Is this the benefit of the demonstrations?”

The comments were not the first time Manet – who did not respond to requests for comment – has expressed frustration with criticism. In January, he lodged a complaint against a Facebook user for linking his family to illegal logging, while in April, after his trip to the US, he questioned why he was condemned by protesters when he, personally, had done nothing wrong.

For young voters like Paññasastra University student Chan Sambath, who hopes Manet will be an agent of change, the scion’s reaction to attacks are an important test. Though Sambath said it was too early to judge Manet’s potential as a leader, he expected someone with his education to be more patient in the face of opponents.

“He should be resistant to criticism,” said Sambath, a researcher for the political discussion group Politikoffee. “His ability to respond to criticism is being tested, so we, [the public], can see how well he can handle that and how much different will he be from his father.”

Regardless of whether any of Hun Sen’s children one day take his place, Manet already occupies senior positions within RCAF as head of the anti-terrorism force and a deputy of both the infantry and his father’s Bodyguard Unit.

A Defence Ministry employee, who spoke on condition of anonymity, said Manet was popular with the rank-and-file, saying he was “like an idol” to young soldiers and always treated older troops with respect.

A long-term military observer, who also requested anonymity, said Manet’s individual clout among military power brokers, however, was difficult to determine as long as the premier remained in charge.

“His father drives the bus . . . and many of those at the top have been riding the same bus, sometimes before he was born,” he said.“His clout would only be measured in the event [his father was gone], and I wouldn’t be putting him first.”

Until April, Manet’s military career had been unassociated with the accusations of human rights violations levelled against the Cambodian state.

That was until a process server served him a lawsuit in the US on behalf of the family of Meach Sovannara, a activist jailed in Cambodia for involvement in a 2014 opposition rally that turned violent. The lawsuit will also be joined by opposition lawmaker Nhay Chamroeun, who was assaulted by soldiers from the Premier’s Bodyguard Unit.

While it presents no apparent evidence directly linking Manet to wrongdoing (though Manet’s bodyguards are accused of assaulting the process server, Paul Hayes), it will attempt to argue culpability based on his rank, plethora of titles and his place in the family.

Its merits aside, the case raises questions about Manet’s responsibility to answer for a government routinely accused of persecuting political opponents.

For Manet supporters like Ky Kalyan, a Cambodian-Australian based in Melbourne who is helping Manet build a CPP network in Victoria, the scion is being unfairly asked to answer for grievances outside his remit.

Working closely with Manet, Kalyan said she had no doubt as to the young general’s honesty and integrity and his desire to improve Cambodia.

“It’s not his job [to defend the government],” Kalyan said in a recent interview. “His mission is to engage the diaspora, to encourage them to come and help the country.”

However, Cambodian-Australian politician Hong Lim, one of the organisers of the recent Melbourne protests against Manet, said that such a sentiment was naive.

As a government representative, Manet was fair game for criticism, said Lim, who has been banned by Cambodia from entering his native country after criticising the regime.

“He’s deep in responsibility; to suggest he’s just a clean-cut kid coming here just to smile and make friendly – you can’t just pick and choose like that.”

Though his own record may have few black spots, it is also difficult to argue Manet has, or even could, push for significant changes, say observers.

Kevin Nauen, senior research fellow at the Cambodian Institute for Cooperation and Peace, said Manet would likely be reluctant to challenge the CPP old guard, whose interests would be threatened by reform.

“Reforms will be challenging even if he is so inclined to pursue them because of the ingrained rent-seeking that permeates the state structure,” Nauen said, adding that rivalry with his brothers may also prove a challenge for Manet to win the support of the CPP as a future leader.

Sebastian Strangio, author of Hun Sen’s Cambodia, said there was no doubt Manet presents a more appealing face for the CPP, calling him well-educated and intelligent. The problem, however, is that the party has not changed, he added.

“There have been more wage-rises and hand-outs, sure, but nothing that can be described as new in substance,” Strangio said. “The party’s strategy is about putting a more youthful spin on an old political message.

“In short, Manet represents a certain amount of future potential, but for the moment, it is just that: potential.”

What’s more, Manet’s own ambitions are far from clear. Pushed during an interview with Australia’s ABC about whether he wanted to one day be prime minister, he paused and appeared unsure about how to respond.

“Do I take that as a yes,” asked the interviewer.

“Not no, not yes,” Manet replied.