CHONBURI — A Chinese national has been arrested after police discovered a cache of military-grade weapons, explosives and bomb-making plans at a rented house in Huay Yai, Bang Lamung district, raising fears of a possible terror plot in the Pattaya area.

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The investigation began when a car driven by Mingchen Sun, 31, overturned in Na Jomtien. Officers searching the vehicle reportedly found a handgun, prompting them to extend their search to a rented property linked to the suspect. A Taiwanese woman, identified as Ma Yu-Hsin, 33, was also in the vehicle at the time of the accident and is being questioned.

During the raid on the rented house, officers said they recovered multiple assault rifles, including M4s, ammunition, grenades, detonators and several blocks of C4 explosive — a powerful military-grade plastic explosive. Authorities also reported finding a bulletproof vest rigged with C4 and connected to a remote triggering system, a discovery so alarming that nearby residents were evacuated while explosive ordnance disposal teams secured the scene.

According to police statements, officers discovered booby traps inside the property, including wires allegedly connected to grenade pins, suggesting the suspect was prepared to defend the location with lethal force. Investigators also found military training videos on the suspect’s mobile phone showing firearms and grenade exercises in Cambodia, including footage linked to the BHQ or “Hun Sen bodyguard” training camp — a facility associated with Cambodia’s elite military units.

Even more disturbing, police said chats on the suspect’s phone showed conversations with ChatGPT discussing sabotage methods, potential targets and the destructive capability of C4 explosives. Authorities are now examining whether the suspect intended to carry out a specific attack and whether he had links to wider transnational criminal networks.

A Chinese man crashed his car near Pattaya and the police find military gear and firearms in the car and his house. Biggest news in Thailand right now the police are saying terrorist from Cambodia but the Chinese man saying depression. pic.twitter.com/FxaPkJsybz

— Personal Thailand (@PersonalThai) May 9, 2026

Additional items seized included gas masks, signal-jamming equipment, fake identity documents and passports from several countries, suggesting a level of sophistication beyond that of a lone individual. Security officials said some ammunition recovered bore markings linked to Thai military production, raising questions about whether weapons or components had been diverted from official sources. Investigators are also examining documents and coded notes found at the property.

The suspect told police he previously operated a liquor business in Cambodia before moving to Thailand. He reportedly claimed the weapons were purchased through a private LINE group several years ago in Rayong province — a statement that, if true, suggests a hidden market for military-grade arms exists in eastern Thailand. He also stated that the explosive vest was intended for suicide because he suffered from depression, a claim that investigators are treating with caution.

Bomb disposal officers later confirmed that the explosive device had been safely defused, but the fact that it existed at all, in a rental property near one of Thailand’s busiest tourist destinations, has sent shockwaves through the security establishment. Senior officers from Provincial Police Region 2 travelled to the scene to oversee the operation, while forensic teams continued gathering evidence overnight.

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Authorities have confirmed that the investigation remains ongoing, with police focusing on the source of the weapons, possible cross-border links and whether additional suspects were involved. The Chinese national is in custody, the Taiwanese woman is being questioned, and the people of Pattaya — who went about their business unaware that a cache of C4 and assault rifles was hidden just kilometres away — are left wondering how close they came to catastrophe. The investigation is far from over, and the answers cannot come soon enough.

-Thailand News (TN)