Updated

The United States and its NATO allies are readying plans to pull away from the front lines in Afghanistan next year as President Barack Obama and fellow leaders try to show that the unpopular war is ending.

Top military and diplomatic officials from the U.S. and NATO allies are meeting this week to finalize the combat handover program and a strategy for world support to the weak Afghan government and fledgling military after 2014.

At the same time, the nations that have prosecuted a war against a Taliban-led insurgency are reassuring nervous Afghans they will not be left to fend for themselves. The competing messages aimed at different audiences are both challenged by current events in Afghanistan, where insurgents staged an impressive, coordinated attack last weekend that struck at the heart of the U.S.-backed government and international enclave in Kabul while Taliban leaders boycott peace talks the U.S. sees as the key to a safe exit.

This week's sessions are meant to stitch together U.S. and NATO agreements on the pace of U.S. and allied combat withdrawal next year. U.S. and Afghan officials have already said they expect a shift to an Afghan military lead in combat operations by the middle of 2013, although the U.S. stresses that it will still have a large number of forces in Afghanistan as backup.

The combat shift parallels the withdrawal in Iraq, where U.S. forces pulled back from lead roles but remained in harm's way for months before a scheduled end to the war. U.S. military leaders have not submitted final proposals for how to ease nearly 70,000 troops into the back seat next year but are working against a firm deadline to end the current combat mission by 2015.

NATO ministers will discuss strategy for the military withdrawal from Afghanistan at a meeting in Brussels on Wednesday, even as violence inside the country mounts and more allies prepare to head for the exits. Diplomats confer Thursday.

The two-day gathering of defense and foreign ministers is intended to clear any obstacles ahead of the conference of NATO leaders in Chicago on May 20-21. Ministers also will address the international bill for sustaining the Afghan army and police after NATO's planned withdrawal at the end of 2014 -- one of the top items on the summit agenda.

Obama also hopes to showcase a long-term security pact with Afghanistan in Chicago. U.S. and Afghan officials said they would like to sign the agreement ahead of the summit, with more specific military agreements to follow.

Afghanistan's president raised another condition Tuesday for that long-awaited deal. He said the accord must spell out the yearly U.S. commitment to pay billions of dollars for the cash-strapped Afghan security forces.

The demand threatens to further delay the key bilateral pact and suggests that Afghan President Hamid Karzai is worried that the U.S. commitment to his country is wavering as the drawdown of foreign forces nears.

The United States acknowledges that despite progress the U.S. is not meeting its goal of drawing $1.3 billion annually from other nations to fund the Afghan armed forces. The U.S. does claim that the largely U.S.-funded effort to recruit and train qualified Afghan military recruits is on or ahead of schedule, with a goal of 352,000 forces later this year.

The Afghan army and police are being expanded rapidly and are expected to grow to 352,000 by the middle of this year. They face about 25,000 Taliban and other insurgents.

Coalition forces, whose numbers reached a peak of over 140,000 troops last year, have already started a drawdown. The U.S., which had about 100,000 service members in Afghanistan, has begun a withdrawal which will remove about a third of them by September.

Other major contributors to the coalition -- including Canada, the Netherlands and France -- have already pulled their forces out of combat or accelerated their withdrawals. Australia on Tuesday became the latest to announce withdrawal plans.

The U.S. already pays the vast majority of the budget to train, equip and run the Afghan security forces and expects to do so for years to come to compensate for Afghanistan's moribund economy. But the yearly congressional budget process, as well as the American public's weariness with the Afghanistan conflict, would make it difficult for Washington to commit to a dollar figure years in advance.

The strategic partnership agreement is crucial to the U.S. exit strategy in Afghanistan. American officials hope it will both map the course for U.S. forces after the majority of combat troops leave in 2014 and give the Afghan people confidence they are not about to be abandoned by their most important international ally.

The talks hung up on what appears to be different views of what the goals of the document should be. U.S. officials involved said it is not meant to set forth exact rules but to establish a framework between the two countries to continue to work together for years to come.

The Afghan government seems to want the exact opposite.

U.S. officials have said they expect to pay about $4 billion a year to fund Afghan forces. Karzai said he wants a written commitment of at least $2 billion. He said he would rather have a firm commitment to a lower figure than a verbal promise for a higher one.

Nearly 3,000 NATO troops have perished in the 10-year conflict, about two-thirds of them Americans.

In the U.S., 6 out of 10 of those surveyed saw the war as not worth its costs, according to a Washington Post-ABC News poll released last month. Opposition to the war is bipartisan, the poll showed.

On Sunday, a small band of guerrillas mounted a brazen strike on embassies, government buildings and NATO bases in Kabul's heavily guarded central district. The violence showed the Taliban and their allies are far from beaten and underscored the security challenge for the Afghan government when foreign backers depart.

U.S. officials blamed the Haqqani network, a Taliban faction considered unlikely to reconcile with the U.S.-backed government in Kabul even if stalled peace talks resume.