BANGKOK | Thousands of U.S. troops began military exercises with Bangkok's military on Monday, while a bloody, four-day artillery duel between Thailand and Cambodia flared on their border and a decades-long Muslim insurgency smoldered out of control in the south.
Cobra Gold, which is scheduled to conclude Feb. 18, is one of the world's biggest multinational, land-based maneuvers. It involves 11,220 people, including 7,200 U.S. service members.
U.S. and other foreign forces are using Thailand's Vietnam War-era Utapao Royal Thai Navy Airfield in Chanthaburi province and other facilities, about 280 miles southwest of the fighting along the Thai-Cambodian border.
The U.S. Marine Aircraft Group 36, 1st Marine Aircraft Wing, 3rd Marine Expeditionary Force, is deployed in Korat, about 180 miles west of the clashes.
U.S. boots are on the ground in this Buddhist, Southeast Asian ally, while a shooting feud between Thailand and Cambodia has killed at least seven people and wounded dozens more.
During the past four days, Thailand and Cambodia attacked each other's jungle-based positions with artillery, mortars, rocket-fired grenades and other weapons, pausing on occasion before shooting again.
They fought for at least one hour Monday after Cambodian Prime Minister Hun Sen said, "We need the United Nations to send forces here and create a buffer zone to guarantee that there is no more fighting."
Both sides then agreed to an unofficial cease-fire, but Thailand rejected U.N. intervention and insisted on direct talks with Cambodia.
Elsewhere in Thailand, the U.S. military's 30th Cobra Gold planned several live-fire demonstrations and other assaults.
Thai Lt. Gen. Surapun Wongthai serves as exercise commander, with U.S. Marine Lt. Gen. Kenneth Glueck Jr. as deputy commander, the Stars and Stripes newspaper reported.
Among the U.S. Marine units participating in Thailand are: Okinawa's 31st Marine Expeditionary Unit, with the 2nd Battalion, 5th Marine Regiment acting as its ground combat element; Marine Wing Support Squadron 172; Marine Aircraft Group 36; and Combat Logistics Regiments 35 and Combat Logistics Regiment 3, it said.
The Sasebo, Japan-based USS Essex, USS Germantown and USS Denver are also involved.
Cobra Gold training exercises include troops from Japan, South Korea, Singapore and, for the first time, Malaysia.
An amphibious assault is scheduled for Thursday on Thailand's southern Hat Yao coast. The cross-border fighting by Thailand and Cambodia was not expected to spill into areas used by Cobra Gold.
Each side repeatedly said the other country's forces fired first after shells landed in Thailand and Cambodia, hitting villages, setting homes and shops on fire and forcing hundreds of people to flee.
Bangkok and Phnom Penh both claim to own the thin slivers of border land near the stone rubble of an 11th-century Hindu temple built by Cambodians when their Khmer kingdom stretched across much of present-day Thailand.
The cross-border fighting damaged the Preah Vihear temple, which was part of an ancient network of scattered Hindu shrines when Cambodia's nearby Angkor Wat complex served as a center of political and spiritual power more than 900 years ago.
Preah Vihear also occupies a strategic military position because it is on a high cliff overlooking northern Cambodia's flatlands 1,722 feet below, about 150 miles north of Phnom Penh, the Cambodian capital.
If Thai forces can dominate Preah Vihear or its surrounding territory on Thailand's eastern border, they would have a high-ground position against Cambodia, making both sides wary of each other's military forces close to the Dangrek Mountains' cliffside zone.
"Thailand is gravely concerned about the use the temple of [Preah Vihear] by Cambodia for military purposes," Thai Prime Minister Abhisit Vejjajiva wrote to the U.N. Security Council on Monday.
The United Nations Educational, Scientific and Cultural Organization has designated the temple as a World Heritage Site. Both countries want to profit from the growing number of tourists visiting the ruins and stopping at restaurants, shops, hotels and other facilities during their travels.
The International Court of Justice awarded the temple to Cambodia in 1962, but a 2-square-mile area on the surrounding cliff is disputed as both countries point to different historical maps.
The office of U.N. Secretary-General Ban Ki-moon in New York said on Sunday, "The secretary-general appeals to both sides to put in place an effective arrangement for cessation of hostilities, and to exercise maximum restraint."
Bangkok's internal political problems are also a wild card in the volatile mix, which could concern Cobra Gold.
Gen. Prayuth Chan-ocha, the Thai army chief, announced in January that he "did not want to stage a coup" despite his role in a 2006 putsch.
Thailand's military has staged more than 18 coups and attempted coups since the 1930s. The most recent, in September 2006, overthrew the popularly elected government of Prime Minister Thaksin Shinawatra.
In April and May, the army battled pro-democracy Red Shirts who blockaded Bangkok's streets, resulting in 91 deaths — mostly civilians — amid protests against the coup and demands to restore Mr. Thaksin to power.
The Red Shirts did not oppose last year's Cobra Gold. However, Sean Boonpracong, a Red Shirt spokesman at the time, warned, "If the United States ignores us, we would put forth more opposition to the next Cobra Gold exercise" in 2011.
"We have tens of millions of followers," said Mr. Boonpracong, who later distanced himself from the Red Shirts after being detained briefly by the army last year.
In 2004, the poorly disciplined Thai army suffocated more than 78 minority Malay-Thai Muslim men after tying them up and laying them flat on top of one another in army trucks.
Each year, London-based Amnesty International and other human rights groups report allegations of extrajudicial killings and torture committed by the army in the south, along Thailand's border with Muslim-majority Malaysia, where an unstoppable insurgency has left more than 4,000 people dead on all sides since 2004.