Updated

Afghan forces will soon start taking charge of security for three-quarters of the nation's 28 million people, NATO's top military commander said Wednesday, a milestone as the country assumes the lead for protecting the majority of its population.

Adm. James Stavridis also insisted the training of the Afghan army and police was proceeding very well, despite attacks in which Afghan soldiers have turned their weapons on their U.S. and NATO partners.

"Very shortly we will announce further transition that will encompass 75 percent of the population," Stavridis said in an interview with The Associated Press. He did not elaborate further on the exact timing of the announcement.

NATO leaders are meeting in Chicago in May to map out a strategy to support the Afghan security forces after the withdrawal of most allied troops at the end of 2014. NATO forces have already handed over authority for about half the population, including the capital, in the first two tranches of a transition that started last year.

This is the first public prediction that after the third phase occurs Afghan security forces will be assuming the lead for protecting the majority of the population.

The war has been increasingly unpopular in both the United States and Europe, where governments are focused on cutting defense expenditures as part of wider austerity measures.

The NATO training mission has been hit hard recently by a series of attacks by members of the Afghan security forces. Last month, a gunman killed two senior U.S. military advisers involved in the training program in an attack inside the Interior Ministry in Kabul. The Taliban has claimed responsibility for the killings, saying it was in retaliation for the burning of Qurans at a U.S. bases.

Stavridis said the target of over 350,000 security forces members will be achieved this summer, several months ahead of plans.

"The strategy is sound and is providing results," he said. "I expected good performance from the Afghan National Army (after 2014) ... they are a very proud army, led by experienced combat officers."

The process of transitioning to Afghan lead was accelerated last year.

Instead of a six-stage process, the plan was changed to now achieve the transition in five steps, with the last starting as early as mid-2013 instead of 2014 -- when most NATO troops are scheduled to depart Afghanistan.

Long-term funding for the force -- estimated at over $4 billion a year -- and how contributions would be divided up between coalition members and other donors, remain unresolved.

"It's important that all ... ISAF nations and other nations involved in international effort contribute to Afghan security forces post 2014," Stavridis said.

Stavridis, the first Navy admiral to serve as NATO's supreme commander, is part of the military and political team assembled by President Barack Obama to conduct the war. The group includes Anders Fogh Rasmussen, NATO's civilian chief.