Opposition leader Sam Rainsy said on Saturday that Prime Minister Hun Sen’s ruling Cambodian People’s Party will be reduced to “a bunch of rebels who will be crushed” by his new government and the nation’s armed forces after the 2018 national election.

The comment, which he later called a “bluff”, was posted in English on Rainsy’s Facebook page along with a speech the opposition leader delivered in the US, where he arrived last week for a series of meetings with government officials and the expatriate Cambodian community.

“In 2018 the CNRP will form a new and legitimate government and what will remain from Hun Sen’s CPP will just be a bunch of rebels who will be crushed by the legitimate government commanding the national armed forces with the support of the international community,” Rainsy wrote in the post.

He also said he believed Vietnam, the historic benefactor of the CPP that installed Hun Sen in power in 1985, would stop supporting the party if the 2018 election revealed it had lost support. “As true as China has stopped supporting the Khmer Rouge as she did 40 years ago, Vietnam – which now needs the support of the USA against China – will be realistic enough to stop supporting Hun Sen’s CPP as she has done over the last 40 years or so,” he said.

In a speech in the video, Rainsy discusses the prospect of the CPP rejecting the election result and trying to keep power, and makes similar comments about the CNRP ending the resistance.

In an email, Rainsy called his comments a “bluff” that should not be interpreted literally.

“The Facebook post is my response to Hun Sen’s bluff. Hun Sen threatens the Cambodian people with a civil war if – I would say, when – his CPP loses the next elections. It’s just a bluff on Hun Sen’s part, and we have to respond accordingly,” Rainsy said.

“The CNRP-led government and administration will welcome and treat with dignity all former CPP supporters,” he said, predicting a “disintegration” of the ruling party that will begin with next year’s commune elections.

CPP spokesman Sok Eysan yesterday said he was not interested in Rainsy’s Facebook comments, and declined to respond either to the threat or whether the ruling party might indeed “rebel” against a CNRP government if the opposition won in 2018.

“Winning the elections – he has talked about that for more than 20 years. Is it the truth? It has not been the truth,” Eysan said. “The ruling party does not have the belief that he will win an election.”

Rainsy’s strong words were a stark departure from the Cambodia National Rescue Party leader’s past comments about the coming elections, and the prospect of his party winning, which has included suggestions of coalition-building and always indicated a peaceful transfer of power.

Rainsy has also been one of the most vocal critics of pro-CPP partisanship in the military. Many top military leaders are allied to Hun Sen, with some even holding positions in the ruling party’s elite standing committee or the larger central committee, and the CNRP and other observers have expressed concerns about the military intervening into politics on behalf of the CPP before.

Over the past year, a litany of high-ranking military and police officials have pledged fealty to the ruling party in public speeches, with four-star General Neang Phat telling hundreds of troops in January that the CNRP “destroy[s] our nation” and “we must go against them”.

Koul Panha, director of local elections monitor Comfrel, said that he still believed the 2018 election would pass peacefully but added that any threats from people like Rainsy about CPP rebels being “crushed” by a future CNRP government would not help that situation to play out.

“It’s an emotional statement. It is not a practical solution. I hope that there are not more emotional statements like this,” Panha said. “We need a long-term vision for Cambodian democracy.

“I think he may be concerned about recent statements from Hun Sen about the possibility of civil war [if the CNRP wins an election], but I am still confident it will be peaceful if there is change. I am hopeful the election results will be respected, and that there will be peace.”

Ou Virak, the head of the Future Forum policy think-tank, said he did not believe Rainsy was in a position to use language intimating a military response to the CPP given the current balance of power in Cambodia.

“He’s upping the ante, but I don’t think he’s in the right position to do that,” Virak said, explaining that encouraging Hun Sen’s party to allow free and fair elections in 2018 should be Rainsy’s main task.

“His statements should not focus on crushing rebels. Speaking of the other party as an enemy has no place in a democratic society,” he added. “What’s most important? It’s that there can be a peaceful transition.

“His message should be that if they win – and that’s a big ‘if’ – they need to prepare for a peaceful transition and for reconciliation, by creating trust that the CNRP has not decided to witch-hunt opponents.”