This Week With(out) George Stephanopoulos, national security advisor John Brennan talks about the loss of seven CIA officers in the recent Afghanistan suicide bombing:

MORAN: This has been a hard week for the CIA. There were seven CIA officers killed in a suicide bombing on the Afghanistan-Pakistan border. What can you tell us about how that attack occurred, and how badly will it impact U.S. intelligence gathering in Afghanistan?

BRENNAN: Well, first of all, I think the tragic deaths of those seven CIA officers just underscores the tremendous bravery and the risk that these men and women of the CIA put themselves at every day. I think this nation owes them a tremendous debt of gratitude.

CIA is looking very carefully at the circumstances surrounding that attack and trying to make sure it doesn't happen again.

The CIA is on the front line, right along that border between Afghanistan and Pakistan. As you point out, it is going to take a toll as far as the people that are there, the expertise that we have. But the CIA is a tremendously resilient organization. I had the privilege to serve there for 25 years. It has some of the most dedicated men and women in this United States, and so therefore we're confident that the CIA is going to be able to rebound from this and be able to continue to prosecute this war against Al Qaida.

MORAN: Should they be out on the front line like that?

BRENNAN: Yes. This is a very, very dangerous threat that Al Qaida poses to us. We have to take those risks. We have to do it prudently, and that's why we have to learn from the attack, just like the attack on the 25th of December, the attack against the base in Khost. But we need to take those risks, because we're -- we need to be able to find out sort of who these individuals are, what they're planning and what their next steps are.

In the meantime, details are still murky:

A CIA investigation is under way into how the bomber was able to circumvent security at the base, apparently passing unchecked through an outer perimeter manned by Afghan contractors to enter the gym and detonate his explosive vest. He was said to be wearing Afghan army uniform, but the Afghan Ministry of Defence has denied he was a member of the security forces.

What is clear, given the number of CIA agents at the meeting, is that he was considered an important informant. One agent had flown in specially from Kabul.

When the CIA is used specificially to circumvent legal restrictions on the military, history shows their operations usually create more problems than they solve (i.e. Vietnam, Thailand, El Salvador). Maybe it's time we had a frank discussion about that:

The C.I.A. has always had a paramilitary branch known as the Special Activities Division, which secretly engaged in the kinds of operations more routinely carried out by Special Operations troops. But the branch was a small — and seldom used — part of its operations.

That changed after Sept. 11, 2001, when President George W. Bush gave the agency expanded authority to capture or kill Qaeda operatives around the world. Since then, Washington has relied much more on the Special Activities Division because battling suspected terrorists does not involve fighting other armies. Rather, it involves secretly moving in and out of countries like Pakistan and Somalia where the American military is not legally allowed to operate.