Bangkok/Phnom Penh - Thai Army Second Lieutenant Baramee Sricha was on a patrol near a disputed stretch of the border between Thailand and Cambodia on July 16, when a member of his team stepped on a landmine that detonated, severing his ankle.
The incident was a catalyst to five days of hostilities, opens new tab between the neighbours, which ended with a U.S.-brokered ceasefire. It also sparked a diplomatic row over PMN-2s - a Soviet-origin anti-personnel mine that litters parts of Cambodia and which Phnom Penh and Bangkok have pledged by treaty not to use.
Thailand accuses Cambodia of laying the mines along parts of their joint frontier and says PMN-2s have maimed at least six Thai soldiers since July, including the member of Baramee's patrol.
Cambodia denies the accusations. It says that some Thai soldiers stepped on non-PMN-2 ordnance planted during a decades-long civil war that left it as one of the world's most heavily mined countries.
Phnom Penh has since positioned itself as a global advocate against the use of landmines. It has invested some $1 billion alongside foreign donors over the past 30 years in demining operations.
Any use of anti-personnel mines by Cambodia, where tens of thousands have been killed or maimed by such ordnance since 1979, would mark a disappointing reversal in decades of public commitments, said Yeshua Moser-Puangsuwan of Landmine Monitor, which is part of the International Campaign to Ban Landmines.
It would also come as some European nations threatened by Russia pull out of the Ottawa Convention, opens new tab, which bans the use of anti-personnel landmines. They join major powers like Washington, Moscow and Beijing, which are not signatories to the treaty.
Thailand's military provided Reuters with access to videos and photographs of what it said were subsequent PMN-2 demining operations carried out by its troops around the site of the July 16 incident, as well as another border-area mine blast on July 23.
During an August visit to frontline Thai military units, the news agency took photos of shrapnel that service members said they recovered from those incidents, as well as images of dozens of intact mines Thailand said were retrieved from along the border area.
Reuters examined the metadata on seven of the supplied images, which show they were taken at the same time as Thai demining operations carried along the frontier between July 18-23 that were listed in two undated military documents about landmines on the border seen by the news agency.
The metadata did not include location information and Reuters was not able to confirm independently where the images were taken.
Four independent landmine experts, asked by Reuters to evaluate the material, said the images depicted PMN-2s that had been freshly laid. However, the analysts were not able to determine who placed the ordnance.
The Cambodia Mine Action and Victim Assistance Authority (CMAA), a governmental agency that oversees demining activities, told Reuters that a determination on the incidents could only be made after an impartial third-party investigation. Cambodia's military does not have stockpiles of live anti-personnel mines, it added.
CMAA's First Vice President Ly Thuch, who reports directly to Prime Minister Hun Manet, said visual appearance alone is not conclusive proof of age.
“Environmental and disturbance factors can make long-buried items appear relatively fresh,” he told Reuters.
A Thai foreign ministry spokesperson said Bangkok's investigations had determined that the landmines that injured its soldiers were newly planted PMN-2s: “They were found in new condition, still with clearly visible markings."
Bangkok is a longtime U.S. ally which did not have widespread access to Soviet-origin munitions and says it has never deployed the PMN-2.
The defence ministry of Russia, which previously said it stopped manufacturing PMN-2-type mines in the late 1990s, did not respond to Reuters’ questions.
The condition of the PMN-2s in the visuals taken by the Thai military and Reuters indicates they had been in the ground for no longer than a few months, said U.K.-based independent expert Andrew Vian Smith.
There are tell-tale signs on older PMN-2s, Smith said: their pliant plastic casing becomes brittle over time and they also have a rubber disc that in most soil conditions quickly becomes dull, collecting dirt in the gaps.
"The mines I was shown had nothing in those gaps," said Smith, who has worked on operations in Cambodia.
The mines were not covered by roots and vegetation as one would expect if they had been in the ground for a long time, said Moser-Puangsuwan.
CMAA’s Thuch said that soil erosion, flooding and shifting vegetation could lead old mines to appear newer than they are.
Moser-Puangsuwan said that flooding might explain a mine shifting position but that such factors don't make ordnance look new.
"Ignoring the absence of other signs of ageing, it is not credible that floodwater could clean these mines and then bury them tidily again," Smith said.
The CMAA has said in a public statement that the mine that exploded on July 16 was not a PMN-2, instead suggesting that mines of American, Chinese or Vietnamese origin might have been responsible.
Asked how it made the determination without access to the injured Thai service members, Thuch said it was a preliminary assessment of "the injury pattern reportedly observed ... (based) on the limited open information available to us."
Reuters' images of the remnants from July 16 include an “initiation delay bellows” - a device that is compressed to trigger the mine's firing mechanism - while photos of the July 23 shrapnel show a spring wire, both of which Smith said were characteristic of the PMN-2.
Thuch said fragment recognition from photos has inherent limits. And there was no verified evidence of local stockpiling or unsanctioned use of mines in the area, he added.
Diplomatic Pressure
A succession of civil wars, including those involving the genocidal Khmer Rouge regime, convulsed Cambodia for some two decades from 1970.
The conflicts left behind one of the world's most densely mine-contaminated areas: a 1,046 km-long stretch along the Thai-Cambodia border.
Demining efforts began in earnest after a 1991 peace accord. More than 3,200 square kilometres of land has since been cleared of unexploded ordnance.
However, PMN-2 mines, which were among the most commonly-deployed in Cambodian and contiguous territory, continue to litter the countryside. Some 1,800 PMN-2s have been found and deactivated since September 2023, CMAA said.
The Ottawa Convention requires contracting states to "destroy all stockpiles of landmines they possess within 4 years" of signing up, said Moser-Puangsuwan.
Thailand is applying diplomatic pressure through the convention and has asked United Nations chief Antonio Guterres to request that Cambodia respond to its allegations through a compliance mechanism built into the treaty.
The convention provides a clear mechanism to address compliance issues, said Farhan Haq, deputy spokesperson for Guterres, adding that the Secretary General would "continue to support efforts in that sense and hopes that Thailand and Cambodia will achieve a cooperative resolution."
Bangkok has also repeatedly petitioned member states party to the treaty since July. It argues that Cambodia has violated the convention by stockpiling and using landmines as well as having previously declined joint demining operations along the disputed border.
