American forces are guarding Marine Pfc. Joseph Scott Pemberton, yet a ring of Filipino troops surrounds them. The seemingly redundant security effort around the suspect in a Philippine murder case reflects Manila's uneasy ties with Washington, its former colonial master.

Pemberton, 19, is accused of killing Jennifer Laude, a 26-year-old Filipino, in a motel room Oct. 11 in the city of Olongapo. He was initially been held on a U.S. Navy warship at the Subic Bay Freeport, northwest of Manila, but on Wednesday he was transferred to the Philippine military's main camp, where Filipino troops and two of his fellow Marines continue to guard him.

Here are some questions and answers about the tensions that result when U.S. troops are accused of serious crimes in the Philippines, whose love-hate relationship with Washington has been shaped over the decades by war, terrorism and now, jitters over China's rise:

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Q: WHAT ARE THE RULES WHEN A U.S. SERVICE MEMBER IS ACCUSED OF A CRIME IN THE PHILIPPINES?

A: Under the Visiting Forces Agreement, which the treaty allies signed in 1998, the Philippines can prosecute U.S. troops accused of crimes there. But the accord grants the U.S. custody over those troops "from the commission of the offense until completion of all judicial proceedings."

Left-wing groups and nationalists have demanded that the Philippine government take immediate custody of Pemberton, saying Americans continue to impinge on their country's sovereignty nearly 70 years after it gained independence. In a compromise between the two countries, the U.S. transferred Pemberton to Philippine soil but continues to guard him and officially has not given up custody.

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Q: HOW DID THE AGREEMENT COME ABOUT?

A: After World War II, the U.S. maintained huge military bases in the Philippines for nearly a half-century, but those were shuttered in the early 1990s amid rising nationalism, virtually freezing military ties.

China's 1995 seizure of a contested reef, however, prompted Manila to reach out to Washington again. Three years later, the allies signed the Visiting Forces Agreement, allowing large-scale military exercises to resume in the country. It also gave the Philippines a clear right to prosecute U.S. troops who commit crimes, something it lacked previously.

Territorial disputes continue to simmer between China and the Philippines over islands in the South China Sea, and occasionally spark direct confrontations. In April, Manila and Washington signed a 10-year defense accord that will give American forces greater access to Philippine military camps.

With its anemic military, the Philippines aims to bolster ties with the U.S. to try to deter China. Washington, meanwhile, is strengthening its military in Asia after years of heavy engagement in the Middle East and Afghanistan.

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Q: WHAT ROLE HAS THE VISITING FORCES AGREEMENT PLAYED IN PAST CASES?

A: The highest-profile, and to many Filipinos most infamous, case was against Lance Cpl. Daniel Smith, who was found guilty and sentenced to life in prison on charges of raping a Filipino woman in 2005. He was held at the U.S. Embassy in Manila until a Philippine appeals court overturned his conviction in 2009, allowing him to leave the country amid anti-U.S. protests.

In 2009, then-U.S. Ambassador Kristie Kenney advised Washington about the dilemma Smith's case created.

"It is imperative that we recognize that more than a legal case, the accusation against LCpl Smith struck at the very heart of Philippine historical animus toward its colonial past," Kenney wrote in a confidential diplomatic cable published by WikiLeaks. "For the last three years, no story ... matched the headlines in column inches devoted to the sordid details" of his case, she wrote.

With Philippine officials dead set against a repeat of the circumstances of the Smith case, they reached a deal with the U.S. that allows both sides to say they have control over Pemberton.

Foreign Secretary Albert del Rosario said Wednesday that Washington "is fully aware that for the Philippine government, it will be totally unacceptable for them to detain Pemberton within the premises of the U.S. Embassy, as was done in the Lance Cpl. Daniel Smith case."

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Q: HOW ELSE DOES HISTORY AFFECT THE U.S. MILITARY'S RELATIONSHIP WITH THE PHILIPPINES?

A: America's foray into the Philippines started when it defeated the Spanish fleet in the Battle of Manila Bay in 1898, ending more than three centuries of Spanish colonization. But the Philippines was ceded shortly after to the United States and only gained independence in 1946, a colonization that was disrupted by the Japanese imperial army's invasion.

Following U.S. forces' exit and return in the 1990s, the Sept. 11, 2001, attacks brought the two militaries closer. Filipino officials allowed hundreds of American counterterrorism troops to train Filipino forces fighting al-Qaida-linked militants in the south. U.S. counterterrorism forces began to scale down their presence in the south this year after helping weaken Abu Sayyaf extremists.

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Q: COULD THE PHILIPPINES DECIDE TO SCRAP THE VISITING FORCES AGREEMENT?

A: The murder case has reignited calls, even among some Philippine senators, for the repeal of the agreement. But that is unlikely because of the security implications: Abrogating the deal could effectively halt current U.S. troop presence and large-scale exercises in the Philippines. President Benigno Aquino III has strongly opposed calls from left-wing activists to scrap the pact, but the government is open to a review of the agreement, including provisions on criminal jurisdiction and custody.

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Q: WHERE DOES PEMBERTON'S CASE GO FROM HERE?

A: Laude's family has filed a murder complaint against Pemberton before government prosecutors in Olongapo, the city northwest of Manila where she was killed. If prosecutors assess there is strong evidence, Pemberton will be indicted and face trial.

Meanwhile, the Marine will likely remain detained in an air-conditioned van, equipped with a sink and a cot, at a U.S.-Filipino compound in the Philippine military's Camp Aguinaldo in metropolitan Manila.

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Jim Gomez, chief correspondent of The Associated Press in Manila, has focused on security and terrorism issues in the Philippines for The AP since 2001.