The National Military Police have been put on alert and are ready to intervene to defend the legal government and prevent any attempts at a “colour revolution” in the country – or such was the message coming from the force’s Deputy Commander Vong Pisen a day after the surprise arrest of opposition leader Kem Sokha on Sunday.

The Cambodia National Rescue Party president was arrested around midnight on Sunday, and has since been charged with “treason” and placed in pre-trial detention in a Tbong Khmum province prison, for saying in a 2013 video that he had received assistance from the United States to plan his political career.

The next day, Pisen ordered personnel in Phnom Penh and the provinces to be on alert and await any order from higher ups to deploy their “forces”, “trucks and armoured vehicles” for a crackdown.

“All Military Police units must respect and adhere firmly to the government’s orders, the Ministry of Defence, Royal Cambodian Armed Forces and National Military Police Commander to protect the legal government and be determined to prevent the colour revolution from happening in Cambodia,” he said in Phnom Penh.

Colour revolution has become a buzzword among government and military officials, and refers to the largely peaceful citizen movements that have toppled regimes in the former Soviet Bloc and Middle East. In recent days, the term has picked up greater currency, with conspiracy theories about a US-backed colour revolution swirling on government-aligned media ahead of Sokha’s arrest.

Pisen asked his officials to control the information flow about Sokha’s arrest by offering “education” to lower officers and staffers about US involvement in the Lon Nol-led coup in 1970, and to help them identify the “tricks of the enemy” attempting a colour revolution.

The diktat also follows a stream of violent rhetoric employed prior to and following the commune elections in June. Before the poll, Defence Minister Tea Banh vowed to “smash the teeth” of protesters who disputed the election results, and Prime Minister Hun Sen told his opponents to “prepare their coffins” because he was ready to kill hundreds to maintain stability.

The Military Police has also had a chequered record for its involvement in violent crackdowns, including the violent dispersal of opposition supporters and garment workers during demonstrations following the 2013 election, as well as its suppression of an alleged “secessionist” movement lead by independent radio station owner Mam Sonando in Kratie province.

Military Police spokesman Eng Hy would only say that Pisen was reiterating the Military Police’s “obligations”, and refused to answer whether the remarks were a direct threat aimed at the CNRP. “The Military Police will follow the Military Police’s role,” he said.

CNRP lawmaker Cheam Channy said the Military Police were only following the country’s current political narrative, but refused to comment further on the issue.

However, political commentator Meas Ny said that in light of increased support for the CNRP in the June commune elections – in which it took an unprecedented 489 communes – the government wouldn’t hesitate to use the armed forces to quell any “uprising” or “rebellion”.

“Second, if this uprising becomes severe, the government has the right to declare an emergency in the country and it will affect the elections. It might be like the military regime in Thailand,” he said.