‘There is a miraculous story that I remember even now,” says Prime Minister Hun Sen, with a pause, in a glossy new documentary that aired in Cambodia on Wednesday night.

Hun Sen was asleep, he recalls in the film, when his “miracle” occurred. “I heard screams on the top of a big banyan tree, saying that I had to leave immediately. Then fire was burning around me like a burning rocket . . . Later, I recalled that dream as an omen.”

The reminiscence is a pivotal moment in the 90-minute Marching Towards National Salvation, which veers between hagiography and propaganda as it explores Hun Sen’s decision to defect from the Khmer Rouge and return with a Vietnamese army to oust the murderous regime. As of yesterday, it had been viewed more than 100,000 times on social media.

The film is the premier’s latest stab at galvanising support ahead of this year’s national election – the validity of which has been called into question by the recent dissolution of the country’s only viable opposition, the Cambodia National Rescue Party, which was accused of fomenting a US-backed “revolution”.

Indeed, Marching Towards National Salvation’s themes of a “US invasion” have notable political expediency, but the film also marks an escalation in Hun Sen’s myth-making efforts.

Dramatic music accompanies the video, with Hun Sen frequently tearing up as he talks about fleeing across the Vietnamese border in 1977, returning over a year later and taking Phnom Penh along with Vietnamese forces on January 7, 1979.

That date is a controversial one. While some view it as liberation from the brutal Khmer Rouge, others see it as the beginning of a years-long occupation by a foreign power – both of which interpretations hold some truth.

Often dubbed the “strongman” of Cambodia, Hun Sen has ruled the Kingdom for more than three decades, but on Wednesday, viewers caught a glimpse of a vulnerable Hun Sen on a hero’s journey straight out of classical literature. “In the world, there was no leader who suffered more pain and bitterness than me,” he says.

The piece doesn’t spare details, from the mediocre to the gruesome – “I always had 12 needles with me to thrust into my throat in case I was seized,” Hun Sen says – but it does feature glaring omissions, some of which reflect Cambodia’s current political climate.

There is no mention of the significant aid the Chinese gave to the Khmer Rouge regime, but several references to Hun Sen fighting against the “foreign invasion” of US bombing.

The spectre of US “interference” has become a ruling party refrain of late, and was used to justify the arrest of opposition leader Kem Sokha in September for alleged “treason”. China, meanwhile, remains Cambodia’s biggest foreign donor and has publicly supported the government’s crackdown on the opposition and dissenting voices.

Hun Sen talks at length about the “genocidal” Khmer Rouge, but takes pains to distance himself from it, despite having been a regimental commander for the regime. In the film, he says he was unconscious when the Khmer Rouge seized Phnom Penh in 1975 and that he “refused” to kill Vietnamese people.

“I made many excuses to avoid that. They were not satisfied with killing their people only and wanted to kill people in the neighbouring country. I did not do that,” he said.

However, the brutal suppression of the Cham Muslim population in the East Zone, where Hun Sen served, was conspicuously absent from the glowing treatment.

Ear Sophal, associate professor of diplomacy and world affairs at Occidental College in Los Angeles, said the personal narrative allowed history’s victors to describe their own version of events, but questioned the effectiveness of recasting the past. “Let’s not forget that the genocide was a result of the very same group of which he was a commander. Can’t erase history,” Sophal said.

There is also no mention in the film of Pen Sovann, the first prime minister to be installed by the Vietnamese who later became an opposition lawmaker, but Hun Sen’s close political allies Heng Samrin and Chea Sim are presented as key players.

Former opposition leader Sam Rainsy called the omissions “an insult to history”, and to the Cambodian people who were expected to swallow it.

“The worst authoritarian regimes always promote [a] personality cult, which in turn leads to [the] distortion of historical facts,” he said.

“This is nothing but pure and cheap propaganda that can be easily and expediently reshaped any time to suit the political objectives of the propagandists.”

Council of Ministers spokesman Phay Siphan, however, defended the documentary. “The prime minister said it, so we understand that it is accurate,” he said. Sebastian Strangio, author of Hun Sen’s Cambodia, described it as “an episode of historical mythmaking whose purpose is less to provide an objective narrative of history (to the extent this is possible) than to burnish Hun Sen’s personal story and justify the CPP’s continued rule of Cambodia”.

“With the CNRP now lobbying foreign capitals to impose sanctions on Cambodia – proffering its own narrative about the death of democracy under CPP rule – Hun Sen and his party are keen to reassert their old claims to legitimacy: that they gave Cambodia its ‘second birth’ after the nightmare of the Khmer Rouge,” he said in an email.

The tale told in the documentary is “not exactly new”, he said, “but the timing and the glossy nature of the project are suggestive, as is the presence of English subtitles. This suggests the CPP is trying to appeal to audiences outside Cambodia as well as at home.”

Online reactions varied, with some criticising the film of whitewashing history.

“The current government also took part [in the Pol Pot regime], so the government has to take a big part of [the] responsibility,” one Facebook commenter said.

“Please also remember in the past that Vietnam invaded Cambodia,” wrote another. Most online commentators, however, praised the premier.

“This video is very important. It shows the truth about the real history which Cambodian leaders went through,” Miech Sopheap wrote.

Still, some had no trouble spotting the parallels to today’s events, including the crackdown on the opposition: “They want to show the heroic struggling of Hun Sen with an attempt to stop [a] color revolution,” one user wrote.

Human Rights Watch’s Phil Robertson said in an email that Hun Sen was “fooling no one with his efforts to re-write history”.

“The problem is that without a real political opposition to call him out on his lies, his mendacity will likely grow by leaps and bounds as the 2018 election campaign nears,” he said.

Robertson also noted the irony in some of the premier’s closing words in the documentary.

Speaking of the lessons learned from ousting the Khmer Rouge’s Pol Pot, Hun Sen said: “Don’t hope that brutality and cruelty can help you keep power. This lesson must be learned deeply. The more dictatorial and the more brutal, the sooner the collapse is.”

Hun Sen, Robertson said, should listen to his own advice, and recognise that “intimidation, violence and rights abuses are wrong and only serve to more firmly embitter the people against the government”.

Additional reporting by Daphne Chen