PHANOM DONGRAK, Thailand >> A brief cease-fire between Thailand and Cambodia broke down Friday, shattering hopes for a quick end to the border conflict as the two sides exchanged fire for an eighth day and the death toll rose to 16.

Field commanders agreed to the truce in a meeting at the disputed border Thursday. But Cambodian Col. Suos Sothea said the Thai army fired artillery shells into Cambodia again Friday and small arms fire crackled anew around the Ta Krabey temple, which lies in a disputed zone along the frontier.

“We cannot trust the Thais,” he said. “Yesterday they said they’d stop fighting and now they are attacking us again.”

Thai army spokesman Col. Sansern Kaewkamnerd said there had been light clashes late Thursday as well as early Friday. He blamed Cambodia for breaking the deal, saying its “local units might not agree to the talks as easily as their commanders did.”

The director of Phanom Dongrak hospital, about 12 miles (20 kilometers) from the border, confirmed one Thai soldier was killed late Thursday, bringing the total dead to 16.

The border dispute has stirred nationalist sentiment on both sides. But analysts say domestic politics may also be fueling the conflict, especially in Thailand, where the military that staged a coup in 2006 could be flexing its muscles ahead of elections due in June or July.

The conflict involves small swaths of land along the border that have been disputed for more than half a century. Including the latest fighting, clashes have broken out six times since 2008, when Cambodia’s 11th-century Preah Vihear temple was given U.N. World Heritage status over Thailand’s objections.

Talks with Cambodia have apparently become divisive within the Thai government, with the military dragging its feet while Prime Minister Abhisit Vejjajiva is more conciliatory.

On Thursday, Indonesian Foreign Minister Marty Natalegawa said his Thai counterpart had agreed to allow Indonesian observers to be sent in. Cambodia had already agreed to the deployment.

Indonesia, which currently chairs the Association of Southeast Asian Nations, offered to provide the observers after four days of border fighting in February.

Analysts say the conflict is primarily being driven by domestic tensions within each country rather than tensions between them.

Neither side appears to be trying to capture territory, and few believe the conflict will evolve into full-scale war. But “key constituencies in both nations are benefiting too much from the border dispute to allow it to die out completely,” Joshua Kurlantzick, a Southeast Asia fellow at the U.S. Council on Foreign Relations, wrote on the organization’s website.

Some believe Thailand’s military, which overthrew former Prime Minister Thaksin Shinawatra in the 2006 coup, fears the Thaksin-allied opposition Puea Thai party may win the expected elections. One theory says top commanders may have been using the skirmishes “to create an atmosphere of uncertainty” within Thailand to derail that outcome, said Dr. Pavin Chachavalpongpun, a fellow at the Institute of Southeast Asian Studies in Singapore.

“If the country is in crisis,” Pavin said, “the military can ask, is it ready to hold the vote?”

Duncan McCargo, a Southeast Asia expert who heads the school of international studies at Britain’s University of Leeds, agreed. The border war “reflects the military’s determination to demonstrate that only the armed forces can be trusted as the guardians of Thai national interests,” he said.

The Thai military has played a prominent role in politics, staging 18 coups since the 1930s. However, it denies that it is now intervening and says — like Cambodia’s military — that it has merely been defending against foreign aggression.

Many believe the fighting also benefits Cambodian Prime Minister Hun Sen, allowing him to portray himself as a victim of a “bullying” Thailand.

One editorial in a Thai newspaper suggested that Hun Sen, who has been in power since 1985, was fomenting the border tensions to gain support at home and divert attention from what it called the “general public’s increasing resentment toward his dictatorship.”

Kurlantzick said Hun Sen’s son, Hun Manet, is taking advantage of the crisis “to play a larger role in military policymaking, potentially positioning him one day to take over running the country from his father.”

Matt Gertken of the U.S.-based think tank Stratfor also said internal politics on both sides are driving the fighting, “whether it be because of Thai factions pushing the Cambodian issue in order to shape perceptions ahead of the election, or Cambodia attempting to take advantage of Thailand’s internal divisions” for its own ends.

“Ultimately, the conflicts here are within Thailand and Cambodia, rather than between” them, said McCargo.