Good morning, welcome to "this week." Cause for alarm. There is a worldwide alert. We have breaking details on that terror threat. New concerns about that risk to the homeland. Plus, the fresh... See More
Good morning, welcome to "this week." Cause for alarm. There is a worldwide alert. We have breaking details on that terror threat. New concerns about that risk to the homeland. Plus, the fresh intelligence that has officials so spooked and so convinced al qaeda may be poised to strike. Then, our exclusive interview with the president 's top military adviser. Will edward snowden's secrets end up in enemy hands and the man at the center of the domestic spying debate, glenn greenwald, reveals his brand-new report here, live. Plus -- I'll let the people decide. -- Anthony weiner not going anywhere. A republican family feud takes off. Washington politicians only care about bringing home the bacon. This is the king of bacon talking about bacon. And the russian olympics on thin ice. All that ahead this sunday morning. Announcer: From abc news, "this week with george stephanopoulos" starts now. Good morning. I'm martha raddatz. George has the morning off. It's great to have you with us. And we begin with breaking news as more than 20 embassies and consulates are closing around the world right now. And here at home, increased security measures are now in place. Abc news has learned this morning that the intercepted communications that led to the alert indicate terrorists are planning an attack that is going to be big and, quote, strategically significant. Yesterday the white house held an hour's long meeting, high-level meeting with the country's top national security officials to discuss the response to the threat, and we've just learned what went on at that meeting, so let's go straight to jon karl, who is at the white house, and, jon, it sounds like the national security community is really spooked by this. Reporter: No doubt about that, martha. The high-level meetings here at the white house over the weekend are a sign of just how seriously the u.S. Is taki this threat. In fact, officials tell us they believe that there are al qaeda operatives already in place for this attack in yemen and possibly in other countries, as well. The cause for concern are those intercepted communications from the leadership of the al qaeda affiliate in yemen. One u.S. Official telling us, quote, the part that is alarming is the confidence they showed while communicating and the air of certainty about their plans. The official tells us they even talked about their media plan for after the attacks take place. Now, one of the things that is especially concerning about the al qaeda affiliate in yemen is that they have developed techniques to evade western security measures. Specifically officials are concerned about terrorists carrying surgically implanted bombs. As one u.S. Official told us, quote, these are guys who have developed the techniques to defeat our detection methods. Jon, people I've talked to said they don't know exactly what the target, even if it's an embassy or consulate. What do you know about that? right. They've closed those embassies and consulates, martha, because they are strategically significant and would fit that description, but there is no guarantee that this would be an embassy or a consulate. As a u.S. Official told us, we do not know whether they mean an embassy, an air base, an aircraft or trains. Now, we saw last year with attack on the consulate in benghazi, the diplomatic outposts are a possible target but, martha, there is no guarantee this time around that the target list is confined to embassies or consulates. Very frightening, jon, and thank you to you. And while the nsa helped uncover this latest terror threat, there are also new revelations this morning in the controversy over its secret surveillance programs. Glenn greenwald from "the guardian" newspaper has been at the center of all this breaking the story with his interview with edward snowden, and he joins us now from brazil. Good morning, glenn. You're reporting there are new frustrations, frustrations in congress about being thwarted in attempts to exercise oversight. What does that mean, and who is stopping them? Members of congress, members from both political parties actually came to us and showed us all kinds of letters and e-mails that they've been exchanging in which they're trying to get the most basic information about what the nsa is doing and spying on american citizens and what the fisa court has been doing in terms of declaring some of this illegal, some of it legal. Remember, we keep hearing that there's all kinds of robust oversight by congress and we need not worry and yet these members of congress, one who is morgan griffeth and alan graceson from florida showed us and we're publishing this morning very detailed letters trying to get this information and they're being blocked from getting it and they've said and other members have said that they are forced to learn about what the nsa is doing from what they're reading in our reporting. And when you say they're being blocked, how are they being blocked? People are refusing to give it to them in congress? Correct. I think the most amazing thing, one of the most amazing things in this whole episode, martha, is that there is a 2011 opinion, 86 pages long from the fisa court that ruled, that much of what the nsa is doing which is spying on american citizens is both unconstitutional in violation of the fourth amendment and illegal, a violation of the statute. This opinion remains a complete secret. The fisa court has said they have no objection to having it released, but the obama administration insists it has to be secret. Both members of congress and others have been simply requesting to read that and intelligence committee who is led by mike rogers and dutch ruppersberger who receives all things from the industry and have refused to allow them access. That's extraordinary to have a court opinion ruling that the government violated the constitution and the law and not only can't we read it, but our representatives in congress. Edward snowden, do you think he'd ever accept a deal to come back to the united states? I think the concern is whistle-blowers in the united states have become the number one enemy of the united states government, which is incredibly disturbing. McCLATCHEY IS REPORTING GREAT Things, how they equate it with treason and all kinds of program. "The new york times" has, as well, so unless that culture which investigative journalists in the united states have been warning about for several years changes fundamentally, he doesn't believe he can get a fair trial. Whistle-blowers in the united states are put in prison for decades and basically disappeared as we just saw with bradley manning. Unless that stops, he's going to instead exercise his well established right to seek asylum from political persecution. Okay, glenn, thanks very much for joining us this morning.
This transcript has been automatically generated and may not be 100% accurate.