KABUL, Afghanistan (AP) -- Senior American and Afghan officials held talks Saturday to try to iron out the details of a key pact signed a year ago that defines the future of the United States' commitment to Afghanistan.

The Strategic Partnership Agreement outlines a set of principles and general commitments for relations between Washington and Kabul after 2014, when foreign combat troops are to withdraw from Afghanistan. But there is lingering uncertainty over whether either party will be willing or able to stick to the provisions of the pact, which includes several loopholes for both nations.

The meeting Saturday in Kabul between U.S. Deputy Secretary of State William Burns and Afghan Foreign Minister Zalmai Rasoul is the second round of negotiations over how to implement the agreement, which was signed in May 2012 by President Barak Obama and Afghan President Hamid Karzai.

The deal spells out Washington's commitment to Afghanistan over the next 10 years as well as its expectations of Kabul, including free and fair presidential elections next year, pledges to fight corruption, improve efficiency and protect human rights, including women's rights.

Sticking points may include the amount of funds the U.S. provides to Afghan security forces. The two countries are also still squabbling over a separate agreement that would protect from prosecution a residual force of as many as 10,000 U.S. troops who would stay behind after the final withdrawal.

In remarks before Saturday's talks, Burns promised that Washington would stick by Afghanistan and its nascent national security forces after 2014 and the end to the international combat mission.

But the deal allows either country to opt out with a one year's notice, which means that Karzai's successor in next year's presidential elections could scuttle the agreement.

Karzai's election in 2009 was marred by widespread allegations of corruption, vote tampering and election fraud. He denied the charges but the acrimonious aftermath tainted his relationship with the West, which was the most vocal of his critics.

The pact emphasizes a free, fair and transparent election in 2014. Karzai however has been relentless in his criticism of U.S. involvement in Afghanistan's political process, alleging Washington was maneuvering secretly to strengthen his political opposition even though he cannot run for a third term.

Burns denied that Washington was backing any candidate to replace Karzai.

"We are supporting the process and not any particular candidate," he said, adding the elections next year should be "transparent, credible and inclusive."

Burns also repeated Washington's support for the opening of an office for the Taliban in Qatar to provide a venue where Karzai's High Peace Council could meet Taliban representatives to try to find a peaceful end to the 12-year war.

The Taliban have met representatives of about 30 countries, participated in international forums in Tokyo and France, and held backdoor talks with Afghanistan's opposition politicians. But they have steadfastly refused to meet Karzai's representatives including the High Peace Council, calling his government a "puppet."

Karzai recently accused the United States of trying to bring his political opponents and the Taliban together, an allegation the U.S. denied and Burns tried also to dispel in his opening remarks.

"We reaffirm our support for the office in Doha for the purpose of negotiation between the High Peace Council and the Taliban," Burns said.

The U.S. diplomat added that on the security front, Washington is on track to transfer full control of Afghanistan's security to Afghan forces by the end of the year.

There are 350,000 Afghan National Security Forces deployed throughout the country, although there has been criticism that the training, which was rarely more than two months, was inadequate and Karzai has often complained of a lack of military equipment to outfit his forces. NATO officials nonetheless say that this spring, when the weather allows more military activity, is the first of the 12-year war in which Afghan forces have done the majority of the fighting.

The next meeting is scheduled for Washington in October. Rasoul at the last meeting said he expected a conclusion of the talks within eight to 10 months but US is not giving a time frame.

As negotiations lumber along, Afghan analysts said it is difficult to foresee the results of an agreement signed almost one year ago.

"So far we haven't seen any practical steps forward from the Strategic Partnership Agreement," said analyst and former Parliamentarian Abbas Nuyan. "Maybe there are some but if there are we are not aware of it."

"The most important factors ... are security in the country, tensions between Afghanistan and its neighbors, upcoming elections and the fight against corruption, which is a serious issue not just for us but for the international community," Nuyan said.

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Associated Press Writer Kathy Gannon contributed to this report.