Private First Class Andrew Holmes was accused of being a member of a five-person "kill team" implicated in the slaying of three Afghans while stationed in Afghanistan's southern Kandahar province in January 2010.

After negotiations, Holmes pleaded guilty to murder, but not to premeditated murder, during a court-martial hearing at Joint Base Lewis-McChord near Tacoma, in the western state of Washington. He was expected to be sentenced on Friday.

Speaking in a clear voice, the 21-year-old from Boise, Idaho also pleaded guilty to two other offenses: possessing a finger harvested from an Afghan corpse and smoking marijuana in hashish form while deployed.

As part of the agreement, prosecutors dismissed three charges, including the two major charges of premeditated murder and conspiracy.

After entering his pleas, Holmes read a prepared statement explaining his actions on January 15, 2010 and answered questions about the incident from the presiding judge Kwasi Hawks.

According to Holmes, the incident began when fellow soldier Jeremy Morlock motioned for an Afghan boy to come closer.

When the boy was about 15 feet (five meters) away, Morlock threw a grenade at him. Holmes then fired his squad automatic weapon at the boy at Morlock's urging.

"I fired six to eight rounds -- and have regretted it ever since," Holmes told the judge.

The squad had also discussed scenarios to make the killing of Afghan civilians appear justified.

Holmes voiced regret for the killing, admitting it was "reckless" but saying it was not his intention to murder the civilian. Quizzed by the judge, he said he believed the bullets from his gun killed the Afghan boy, not the grenade.

The soldier also recalled his doubts about the Afghan civilian being a threat and called himself "naive" in his assessment of the situation at the time. He was 19 at the time of the shooting.

"He pleaded guilty to doing something reckless that killed a human being," defense attorney Daniel Conway said after the proceedings.

Two other members of the alleged rogue unit, Morlock and Adam Winfield, reached plea deals earlier this year as the US Army works to conclude the high-profile war crimes case.

Morlock received a 24-year sentence in March. In August, Winfield received a three-year sentence after pleading guilty to involuntary manslaughter, saying he was threatened by his platoon sergeant to take part in the killings.

Holmes, along with Morlock, was one of the US soldiers shown posing for the camera with an Afghan corpse, in shocking photos published by German news magazine Der Spiegel.

Two other soldiers -- Michael Wagnon and alleged ringleader Staff Sergeant Calvin Gibbs -- still face charges for their alleged role in the killings.

The soldiers were members of Bravo Company, 2nd Battalion, 1st Division's Stryker brigade, based out of Joint Base Lewis-McChord south of Seattle.

Chairman of the U.S. Joint Chiefs of Staff, U.S. Navy Adm. Michael Mullen, in testimony Thursday before the U.S. Senate Armed Services Committee, said the Haqqani terrorist network, which attacked the U.S. Embassy in Kabul last week and also killed 77 coalition forces in a truck-bomb attack earlier this month, is "a veritable" arm of the Directorate for Inter-Services Intelligence.

"With ISI support, Haqqani operatives planned and conducted that truck bomb attack as well as the assault on our embassy," Mullen said.

"We also have credible evidence that they were behind the June 28th attack against the Intercontinental Hotel in Kabul and a host of other smaller -- but effective -- operations."

News reports have stated that the commander of U.S. and NATO forces in Afghanistan, U.S. Marine Corps Gen. John Allen, also turned up the heat when he revealed that he personally gave Pakistani Army chief Gen. Ashfaq Kayan intelligence information about a possible terror attack and Kayan said he would "make a phone call" to stop it.

The attack was the truck bombing two days later.

The Haqqani network is an Islamist organization in Pakistan's North Waziristan, which is in the Federally Administered Tribal Areas along the border with Afghanistan. It is connected with the Taliban as well as al-Qaida and conducts operations mainly in Afghanistan's Paktia, Paktika, Wardak and Khost provinces as well as in Kabul province.

Its overall leader, Jalaluddin Haqqani, fought Soviet forces in the 1980s, during which time he and his followers received support from Pakistan's ISI as well as from the CIA. It's believed to have as many as 15,000 full-time and part-time gunmen and other operatives.

Haqqani's son, Sirajuiddin, is believed to be in day-to-day operational control and is on a "most wanted" terrorist list of coalition forces.

Pakistan has denied the allegations as baseless. Pakistan is cooperating in the war on terrorism, it said, and is needed by the United States and coalition forces. It also warned Washington could "lose an ally" is accusations continued or if its sovereignty were violated.

Increasing attacks on terrorist leaders in Pakistan by U.S. drones is a particularly sore point with Islamabad, which faces its own problems with Islamist militants.

Analysts say that Pakistan, an early supporter of the Taliban when it came to power after Moscow ended its occupation of Afghanistan, is playing a double if not a triple game with terrorism. It wants to appease the United States, which is a major provider of aid, while pacifying its own Islamists; it wants to exert influence on the government of Afghan President Hamid Karzai; and it wants to insure a strong influence on Afghanistan when Coalition Forces withdraw and the Taliban returns to power.

The United States for years has complained diplomatically about the ISI involvement with Afghan insurgents. When it mounted the raid in Pakistan in May that killed al-Qaida leader Osama bin Laden, Washington didn't inform Pakistan of the operation or the intelligence gathered leading up to it. It simply didn't trust Islamabad -- given previous information leaks.

In the past "rogue" elements within ISI were often accused of supporting the terror groups. But the ISI is described as a highly disciplined organization that takes its lead from military leadership.

The United States may now be putting the rogue theory to rest but what it can do in practical terms is an iffy proposition.

"They need us," a Pakistani official said. And it's true. About 35 percent of supplies for coalition forces in Afghanistan pass through Pakistani ports and are trucked through the country.