In June, Chinese military planes landed in Cambodia over three days, delivering a substantial cache of weapons. This occurred mere weeks before a tense border dispute between Cambodia and Thailand erupted into full-blown warfare.
The aircraft were Y-20s, known colloquially in China as ‘Chubby Girls’ due to their wide bodies and impressive cargo capacity. These planes completed six flights to the southwestern city of Sihanoukville, transporting rockets, artillery shells, and mortars. This shipment, previously unreported, comes to light through Thai intelligence documents reviewed by The New York Times.
These Chinese-supplied armaments, packed into 42 containers, were initially stored at the nearby Ream Naval Base, according to the documents. Days later, Chinese-made ammunition was reportedly moved hundreds of miles north, directly to Cambodia’s contested border with Thailand.
When asked for comment on the Thai intelligence reports, a senior Cambodian official acknowledged many of the fundamental details about the shipment without explicitly denying them.
Thailand and Cambodia each blamed the other for initiating the war, which raged for five intense days in late July. Crucially, before the fighting began, Cambodia’s border buildup included significant arms movements. For months, Cambodia had been fortifying its positions along the boundary near an ancient temple claimed by both nations, constructing new roads and a military base, all clearly visible in satellite images.
Analysts suggest that this extensive preparation allowed Cambodia to adopt a far more provocative stance toward Thailand than it had in previous confrontations. However, both adversaries relied heavily on a common supplier: China, which has cultivated deep strategic and economic ties with both Southeast Asian nations.
Independent monitoring organizations largely corroborate the findings of the Thai intelligence assessment, particularly regarding the origin of some weapons used by Cambodia. Fortify Rights, a human rights group, reported that the rockets Cambodia launched against four Thai provinces were predominantly of Chinese manufacture. On the conflict’s opening day, Thai authorities stated that Cambodia struck a gas station, a hospital, and civilian residences, resulting in at least 13 civilian deaths.
“The totality of the evidence indicates a deliberate decision by the Cambodian leadership, over months and years leading up to these border clashes, to fundamentally alter the status quo along the border,” remarked Nathan Ruser, an analyst for the Australian Strategic Policy Institute.
A senior officer from the Thai Armed Forces, contacted by The Times, verified the authenticity of the intelligence documents. They stated that the information was compiled by an intelligence network spanning various military branches. Two other officers independently confirmed that the documents had been circulated internally within the armed forces. All three spoke anonymously due to the classified nature of the information.
In an official statement, Lt. Gen. Rath Dararoth, Cambodia’s secretary of state for defense, did not dispute the core details of the Chinese weapons shipments to his country. However, he characterized the Thai intelligence reports as “misleading,” claiming that the equipment movements coincided directly with the conclusion of Cambodia’s annual joint military exercise with China’s People’s Liberation Army.
However, that exercise had concluded weeks earlier, in late May. General Dararoth declined to answer further questions.
China’s Defense Ministry did not respond to a request for comment.
Cambodia’s proactive preparation and resupply likely enabled it to sustain the fight longer. Nevertheless, Thailand swiftly asserted its dominance with its considerably more advanced arsenal. Thai forces retaliated with F-16 airstrikes, bombing targets within Cambodia.
By the time a cease-fire was brokered five days later, at least 40 people, including civilians on both sides, had been killed, and hundreds of thousands more were displaced.
China’s Balancing Act
China actively participated in efforts to achieve a cease-fire. Yet, these revelations about weapons shipments complicate Beijing’s ambition to present itself as a neutral mediator in Southeast Asia.
Despite Cambodia’s military budget being a fraction of Thailand’s, both nations have significantly increased defense spending in recent years, turning to China for their arms. Beijing now considerably surpasses the United States as the primary source of weaponry for Thailand, even though Thailand remains a long-standing U.S. treaty ally.
Chinese officials have publicly refuted allegations in the Thai press concerning the arming of Cambodia against Thailand. In late July, a day after hostilities commenced, a high-ranking Chinese military official met with the acting Thai defense attaché in Beijing. The Chinese official maintained that China had provided no military equipment to Cambodia for use against Thailand since the border tensions began.
The Chinese official’s publicly reported statements lacked specific dates.
Tensions initially flared in February after Cambodian soldiers and civilians sang their national anthem at an ancient temple claimed by both sides. A Cambodian soldier died in a skirmish in May, and five Thai soldiers were injured by land mines in July. Cambodia maintains that Thailand initiated the conflict by obstructing access to the temple.
Thai military intelligence reports indicate that from June 21 to 23, China supplied nearly 700 rounds for Soviet-era BM-21 multiple barrel rocket launchers, as well as Chinese-made Type 90B and PHL-03 multiple launch rocket systems. Additionally, China reportedly shipped artillery shells for the SH-1 Chinese self-propelled howitzer and ammunition for Soviet-era anti-aircraft machine guns, the documents detailed.
Over the subsequent two days, Cambodia moved this ammunition to the border provinces of Oddar Meanchey and Preah Vihear, according to the same documents.
Such a substantial series of deliveries would likely have required approval from the highest levels of Chinese leadership, according to analysts.
“This swift level of resupply was clearly not standard operating procedure,” noted Anthony Davis, a Bangkok-based analyst with Janes, a prominent defense and security publication.
A Contested Border
The two-centuries-old temples at the heart of this dispute are situated near a border delineated by France in the early 1900s during its colonial rule of Cambodia. Both neighboring countries lay claim to these ancient sites. In the 1960s, an international court ruled that the Preah Vihear temple belonged to Cambodia, a decision that Thailand, which refers to the shrine as Phra Viharn, has never formally accepted.
Earlier this year, Cambodia appeared to be actively bolstering its strategic position.
It constructed a military base just east of the Preah Vihear temple, affording it a superior vantage point over Thai troops across the border. This new structure could have functioned as an artillery base, according to Mr. Ruser, the Australian analyst. Beginning in late 2022, Cambodia also developed more roads and other infrastructure, which analysts interpret as a concerted effort to militarize sections of the border.
“This fortification occurred across multiple sectors along the border, which refutes the idea that it was merely an individual commander seeking to improve tactical positioning,” Mr. Ruser explained, having analyzed satellite imagery of the area. “This implies a much broader directive from the Cambodian military leadership.”
General Dararoth stated that the new base was part of Cambodia’s routine defense improvements. He further asserted that Cambodia has “no attack doctrine in place” and that its military activities are “not aimed at any neighbor or external actor.”
Hangyu Lee, a researcher with Armed Conflict Location & Event Data, a non-profit organization that monitors global conflicts, observed, “It remains evident that Cambodia’s military buildup was significantly more proactive than Thailand’s.”
In contrast, Mr. Lee noted that Thailand was “largely reactive and defensive.” The Thai Army reinforced existing outposts, built supply roads, deployed artillery and armored assets, and intensified surveillance to match Cambodian activity.
Cambodia labels Thailand the aggressor and has repeatedly accused Thai soldiers of territorial encroachment. It also blames Thailand’s pro-nationalist factions for fueling the border tensions. To resolve the conflict, Cambodia has sought intervention from an independent body, such as the International Court of Justice, a proposal Thailand has rejected.
Cambodia’s Limits and Potential Calculations
Cambodia possesses a military significantly weaker than its neighbor and maintains that it does not desire war with Thailand. So, why would it proceed with deploying troops and weapons to the border?
Some analysts theorize that Cambodia’s de facto leader, Hun Sen, aimed to consolidate nationalist support amid growing economic discontent. Alternatively, his actions might have been driven by a deteriorating relationship with former Thai prime minister Thaksin Shinawatra, whose daughter Paetongtarn Shinawatra was Thailand’s leader during the hostilities.
Others suggest that, following years of sustained Chinese support, Mr. Hun Sen may have felt confident that Cambodia was in a stronger strategic position compared to previous clashes.
During the last major confrontation with Thailand in 2011, Cambodia rapidly depleted its ammunition reserves, according to Rahman Yaacob, a researcher on Southeast Asia’s defense policy at the Australian National University. This critical shortfall prompted Phnom Penh to significantly deepen its military ties with China.
Since 2011, China has indeed emerged as Cambodia’s principal military patron. The two nations have regularly conducted annual joint military drills for the past nine years, with the exception of the coronavirus pandemic period. In 2018, China provided Cambodia with over $100 million in military aid. Analysts now estimate that Chinese weapons constitute the majority of Cambodia’s military arsenal.
“They perceive themselves as far better equipped compared to 2011,” Mr. Rahman observed. “That is precisely why this conflict was so serious, involving heavy weaponry rather than just rifles and small-arms fire.”
Battlefield photographs shared on social media also depicted Cambodian soldiers utilizing Chinese-made SHE-40 122-millimeter artillery rockets, compatible with multiple rocket launcher systems.
“Every piece of ammunition we observed being loaded into the rocket launchers was Chinese-made,” stated Peter Bouckaert, a conflict expert at Fortify Rights, a non-profit organization.
“China should critically assess the Cambodian Army’s conduct during this conflict and voice its concerns about the indiscriminate use of their supplied weapons,” Mr. Bouckaert urged. “Such actions do not enhance China’s global image when its arms are used to kill civilians in other Asian nations.”
Pablo Robles contributed reporting from Seoul, Phuriphat Dejsuphong and Kittiphum Sringammuang from Bangkok, and Li You from Beijing.