Defence Minister Tea Banh, Health Minister Mam Bunheng and Prime Minister Hun Sen’s son Hun Manith all visited Svay Rieng’s Koki commune last week, calling on the US to take responsibility for chemical weapons found there and blaming US chemical bombs for causing deformities in villagers.

Two Vietnam War-era barrel bombs containing CS tear gas were discovered in Koki commune in January. Demining officials began to excavate the bombs last month, following an anti-American tirade from Hun Sen. Since officials descended on the commune, at least 14 more “similar” bombs have been reported.

Bunheng visited the area on Thursday, and according to government-aligned media source Fresh News discovered three villagers suffering from birth defects.

“We have conducted medical checkups for the villagers and found three abnormal children. There are birth defects such as big heads, disproportionate mouths and skin allergies … I believe that it is caused by the US chemical bombs,” Bunheng told Fresh News.

As the government has ratcheted up its anti-US rhetoric in recent months – accusing it of colluding with the opposition to foment “colour revolution” – the bombs have become something of a political talking point.

A Post investigation last month revealed villagers in Svay Rieng living with birth defects commonly associated with Agent Orange, a defoliant used by the US military during the Vietnam War. But many officials, including the prime minister, have claimed the CS tear gas bombs caused birth defects, appearing to conflate the two chemicals, despite medical research to the contrary.

“Police departments around the world use CS gas. We are aware of no scientific studies linking CS gas to the conditions described by the Minister,” David Josar, deputy spokesman at the US Embassy, said in an email on Thursday.

Chemical weapons expert Richard Guthrie agreed that “there is no clear evidence that CS causes birth defects”.

Ly Sovann, spokesman for the Ministry of Health, confirmed in a message yesterday that the defects in Koki were likely caused by “chronic [exposure] to Orange agent weapons”, not CS tear gas.

However, Guthrie warned that conflating the two issues could actually hamper efforts to assist victims of Agent Orange.

“We need to treat these issues with scientific rigour. There is still much restitution needed in relation to the suffering caused by Agent Orange. Misplaced understandings about which substances can cause birth defects could weaken the efforts to get such restitution,” he said via email.

Defence Minister Banh, meanwhile, claimed on Friday that Cambodia has already formally requested assistance from the US but has yet to receive a reply. “We have informed via letter already. But there is no positive answer in time,” he said.

The US Embassy did not respond to a request for comment yesterday, but has repeatedly denied receiving a formal request to help with the disposal.

“For this time, we have made suggestions to confirm about the treaty,” Banh added, referencing the Chemical Weapons Convention (CWC) banning the use of tear gas in warfare.

But Paul Walker, vice chair of the board of the Arms Control Association, has previously pointed out that the CWC was signed in 1997 “so if these CS-filled munitions were used during the Vietnam War, it would not have been a violation”.

Meanwhile, Hun Manith, son of the prime minister and director of military intelligence, said the Ministry of Foreign Affairs would lodge an official complaint with the United Nations.

“Our Foreign Affairs Ministry will urge the United Nations to recognise that Cambodia has remnants of chemical weapons,” Manith said, calling on the US to offer financial and technical support.

The US has contributed $160 million to demining efforts in Cambodia, and continues to supply $2 million annually.

Manith also took the opportunity to accuse the US of not fully recognising the impact of its bombing, saying it did “not accept that they dropped 2.7 million tonnes of bombs”.

Additional reporting by Kong Meta