In his State of the Union address, President Obama reaffirmed that the country's war in Afghanistan would be over by the end of 2014.

He also laid out more specifics.

Of the approximately 66,000 U.S. troops in Afghanistan now, more than half -- 34,000 -- will come home in the next year, Obama said.

At the same time, Afghan troops will assume most of the responsibility for combat missions.

"This spring, our forces will move into a support role, while Afghan security forces take the lead," Obama said.

It was previously expected that Afghan forces would take the lead in combat missions by the middle of this year. But a U.S. official told CNN that the military transition has accelerated and that Afghans will lead all security operations by March.

What does this news mean for Afghanistan and America's longest war? Here are some key questions that will be asked in the coming months:

1. Are the Afghan troops up to the task?

There are certainly doubts.

A Pentagon review in December claimed that only one of 23 Afghan army brigades was capable of functioning on its own.

Meanwhile, literacy rates are low, desertion rates are high, and many deserters have joined the insurgency. There also have been a troubling number of "green-on-blue" attacks: Afghan troops attacking their American comrades.

But Defense Secretary Leon Panetta has spoken positively about the progress Afghans have made in growing their army, reducing violence and becoming more self-sufficient. Afghan forces now lead nearly 90% of operations across the country.

"We're on the right path to give (Afghanistan) the opportunity to govern itself," Panetta said earlier this month.

Afghan President Hamid Karzai said he welcomes the U.S. troop withdrawal and insists his army can defend the country against the Taliban.

"It is exactly our job to deal with it, and we are capable of dealing with it," Karzai said during an interview with CNN's Christiane Amanpour.

What the army needs now, Karzai says, is more equipment and firepower. He came to the Pentagon last month with a wish list asking for more helicopters, drones and other hardware, according to a senior defense official.

"We need an air force. We need air mobility," Karzai told Amanpour. "We need proper mechanized forces. We need, you know, armored vehicles and tanks and all that."

2. What presence will the U.S. have after 2014?

The plan is to withdraw all combat troops but keep a residual force in the country to help train Afghans and carry out counterterrorism operations when needed.

The size of that force is still being discussed.