BANGKOK, Thailand -- The U.S.-trained Royal Thai Navy is gearing up to stop all Thai ships in the Gulf of Thailand transporting fuel and military supplies to Cambodia, the first major use of the artillery-firing navy in the five-month-long border war.

The U.S. Seventh Fleet uses the Gulf of Thailand when its aircraft carriers and other vessels dock near Bangkok at Sattahip port where Thailand's First Naval Area Command is based to secure the gulf, which is peppered with inhabited Thai and Cambodian islands, navy facilities, and oil rigs.

In addition to intercepting Thai ships, including fishing and commercial vessels, the navy said it would stop Thai-owned ships sailing under foreign flags and registrations, if they are suspected of transporting fuel, weapons, ammunition, or other military equipment across the gulf to reach Cambodia's south coast.

Thai shipping companies facilitating their travel, vessels' owners, suppliers, chandlers and others linked to Thai ships violating the ban would also be held responsible, officials said.

The navy warned shippers about "high-risk zones" in the Gulf of Thailand's northeast waters, close to southern Cambodia's beach towns and scattered ports.

That coastline is rife with smugglers, human traffickers, fugitives and others illegally using small boats to avoid crossing the nearby Thailand-Cambodian land border.

"The declaration of a high-risk zone is neither a blockade nor a closure of the Gulf," Navy Spokesman Capt. Nara Khunthothom said.

"This operation concerns a bilateral conflict between Thailand and Cambodia, and our actions must not impact third countries.

"We will take all necessary steps to cut off these supplies," Capt. Nara said.

"This is a peaceful approach to restrict Cambodia's ability to act against Thailand," Defense Minister Gen. Nattaphon Narkphanich told reporters.

In addition to cargo vessels, passenger ferries and other ships, more than 10,000 fishing boats trawl the Gulf of Thailand's shallow waters, Gen. Nattaphon said.

The National Security Council endorsed the Thai Maritime Enforcement Command Center (Thai-MECC) to be in charge of stopping the ships.

The intercepts include maritime surveillance of cargo including transfers while at sea, plus loading and unloading on land, Thai-MECC Spokesman Navy Adm. Jumbol Nakbua said.

Thai geeks, sleuths, shipping experts, military researchers and others have already started tracking suspicious ships in the gulf, and posting their evidence online.

Many of them use MarineTraffic.com to determine ships' locations.

They posted information about a Thai-flagged vessel which allegedly sailed to Singapore to collect fuel on December 10, and then docked and unloaded it at a Cambodian port on December 14.

Several other vessels they tracked had departed from Thailand's Laem Chabang Port, near Bangkok, allegedly carrying fuel to Cambodia.

A handful of Thai shipping companies have legally been sending fuel to Cambodia for years.

The Gulf of Thailand is bigger than the Persian Gulf, covering a surface the size of Poland. The 123,000-sq.-mile (123,550-sq.km.) gulf forms a cul-de-saq in the western Pacific, bordered by Thailand, Cambodia, Vietnam, and Malaysia. 

Thailand shares the Gulf of Thailand with Cambodia.

The navy's interceptions may become hampered by Thai and Cambodian maps of the gulf which document their disputed, overlapping maritime borders around prized undersea natural gas and petroleum zones, and drilling rigs operated by Chevron and other foreign and Thai corporations.

Cambodia's share of the Gulf of Thailand includes nearby Ream Naval Base next to sheltered Sihanoukville Bay.

Washington fears if a U.S.-China war erupts, Ream Naval Base will be monopolized by Cambodia's close friend China which financed and constructed the base's newest facilities allowing deep-water ships to dock, load and unload, and undergo maintenance and repairs.

Cambodia, which recently improved relations with the U.S., insists Ream will remain open to all international shipping.   

Thailand's army recently displayed Chinese-made anti-tank missiles which it seized when Cambodian troops retreated from Hill 500 in Thailand's Ubon Ratchathani province.

Beijing said its "normal defense cooperation" with both Bangkok and Phnom Penh had nothing to do with the border clashes.

China sells weapons to both Thailand and Cambodia.

"China has been working actively for de-escalation," China's foreign ministry said on December 18.

The U.S. is a non-NATO treaty ally with Thailand and conducts several annual military training exercises with Thailand's armed forces, including its navy in the Gulf of Thailand and Andaman Sea.

The Thai navy's main force includes frigates brandishing 127mm guns, and corvettes for coastal patrols and attacks with Bofors 40mm guns.

The navy also owns one aircraft carrier armed with a 20mm Gatling gun. 

The flat-topped vessel is mostly used for helicopters and humanitarian crises such as providing an emergency hospital or flood relief.

The Thai navy is trained by annual U.S.-led military exercises, including Cobra Gold and other multinational drills.

For example, the U.S.-led CARAT (Cooperation Afloat Readiness and Training) exercise focuses on naval partners in Southeast Asia, including Thailand.

CARAT upgrades navies' skills in surface water warfare, diving and salvage, armed patrols, and piloting navy aircraft.

Another U.S.-led exercise, SEACAT (Southeast Asia Cooperation and Training), also concentrates on maritime security.

China's most prominent naval exercises with Thailand include much smaller Blue Strike bilateral drills with China's Marine Corps, Thai Navy Marine Corps, and special warfare units.

They practiced amphibious assaults, anti-terrorism strategies, island seizure, and other maritime confrontations.

Fighting between the two Buddhist-majority nations has, since July, involved mostly air and ground attacks along their disputed frontier.

Clashes along the curved 500-mile-long Thailand-Cambodian frontier continued on December 20.

Last week, Thailand's F-16 warplanes bombed the Ghost Mountains in northern Cambodia's Preah Vihear province, and the outskirts of Poipet town in western Banteay Meanchy province, Cambodia's defense ministry said.

"Hundreds of [Cambodian] BM-21 rockets were fired, not at soldiers, but at farmland and civilian areas," Thai army Spokesman Col. Richa Suksuwanon said on December 18).

"This is not right, and we will surely retaliate," Col. Richa said.

More than 50 people, including 21 troops and 12 Cambodian civilians, have been killed -- plus half-a-million people displaced -- on both sides of the Thailand-Cambodian border war.

Thailand holds 18 Cambodian prisoners of war.

The conflict is concentrated along frontier territory claimed by both nations, causing havoc in Thailand's modernizing northeast border provinces of Surin, Buriram, Sisaket, Ubon Ratchathani, and Trat.

On the opposite side, Cambodia's much less developed provinces hit by assaults during recent clashes include Preah Vihear, Banteay Meanchey, Battambang, Pursat, Koh Kong, and the northern edge of Siem Reap province.

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Richard S. Ehrlich is a Bangkok-based American foreign correspondent reporting from Asia since 1978, and winner of Columbia University's Foreign Correspondents' Award. Excerpts from his two new nonfiction books, "Rituals. Killers. Wars. & Sex. -- Tibet, India, Nepal, Laos, Vietnam, Afghanistan, Sri Lanka & New York" and "Apocalyptic Tribes, Smugglers & Freaks" are available at
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