Gen. John Allen, the former commander of international forces in Afghanistan, said Afghan security forces have proven themselves to be more capable than anyone expected, and will be ready to take over securing the country 2014.

"They turned out to be better than we thought. They turned out to be better than they thought," said Allen.

Allen said he generally was hopeful as he sat down at the Brookings Institute today to give his thoughts on the state of Afghanistan and how it might fare after the U.S. draw-down that starts next year.

He credited the progress made by Afghan security forces to developmental strategies as much as building military capacity, citing the push for literacy within Afghan forces. Allen said the literacy program was championed by international forces commanders - Stanley McChrystal, David Petraeus and then himself - and that he expected Gen. Joseph Dunford to continue the program because of its success. Allen said more than half the Afghan troops now have the capacity to read and write at a first grade level.

"We intend ultimately … to not just emphasize the continuation of that program at the basic or entry level," he said, "but to continue to emphasize the continued learning of the Afghan soldiers and police throughout the period of time when they're enlisted so that this becomes not just an initiative which is useful for military or police operations; it's an initiative that has the potential to change society."

Allen added that despite a turbulent 2012 dealing with the fallout of a video that purportedly showed troops urinating on the corpses of suspected Taliban fighters, the furor over the burning of Korans at a U.S. base in Afghanistan, and an increase in insider attacks, the U.S. was still able to accomplish its major goals for Afghanistan this year, completing the draw-down of 23,000 troops brought in during a surge in force levels and continuing to serve as support for the Afghan forces who are increasingly taking the lead in the fighting. He called the achievement "momentous," noting that already in 2013, U.S. troop positions in Afghanistan mostly are serving advisory roles.

But for all the good news, Allen sounded the alarm on some of the issues that could upend progress. His biggest concern he said was not Afghanistan, but the role it's neighbor Pakistan continues to play in securing peace and stability in the region. He described the relationship between Pakistan, Afghanistan and, by extension, the U.S. as "complicated." He said Pakistan doesn't always get enough credit for the counter-terrorism measures it has taken, but acknowledged that not enough is being done to secure the porous border between the two countries where militants are known to cross easily.

"The border area on both sides remains a principle obstacle and potential problems for a downturn of the campaign," he said, alluding to "safe havens" that he said Pakistan needs to crack down on.

The general said it was unrealistic to expect the insurgency to completely end by Jan 1, 2015.

"The fact that the ISAF mission has ended and resolute support is under way as an advisory mission, there's still going to be fighting," said Allen. "And Afghanistan will join a long and distinguished list of countries that will be struggling in a post-conflict environment, where it will have an insurgency in some parts of that country for an extended period of time."

Allen said the measure of success shouldn't be whether there is still a presence of an insurgency, but whether the Afghanistan security forces and police have the capacity to continue to erode and ultimately defeat the insurgency's power base. Allen believes that, with continued support from the U.S. and other international partners, Afghan security forces will be successful.

He said President Karzai's statements criticizing the U.S. are unhelpful to the partnership, but he said the Afghanistan president was in a "complex" position. Calling Karzai's job "the hardest in the world," Allen said that the leader is constantly stuck between serving his domestic constituency and keeping the international community happy.

"He has to balance his rhetoric for the potential for peace," said Allen. "Sometimes, that rhetoric is harsh. And we don't have to agree with it. We don't have to condone it. We don't have to like it. And on those occasions where I've publicly been confronted - in testimony, primarily - with some of his rhetoric, I, in fact, reject it. And I reject comments which would put our troops at risk, that would put his troops at risk."

Referencing the latest controversy over Karzai accusing the U.S. of colluding with the Taliban, Allen joked, "In fact, if the president truly does believe that the U.S. is colluding with the Taliban, I'm here to tell you: I would know, and we ain't and we don't intend to."

The four-star general got personal as he reflected on the end of his 36-year military career, telling the crowd that serving as the commander of international forces in Afghanistan was the greatest honor of his life. He said he thinks every day about the 561 coalition troops who were killed and 5,500 who were wounded in action fighting under his command.

"While we all may have different views of the war and the struggle and the conflict, none of us should have anything other than the utmost respect for these young women and men who have, in some cases, given everything," he said. "And we should never forget that."