Good morning, welcome to "This week." Olympics alarm. Terror threats. Emergency evacuation plans. The state department issues a brand new travel alert. And a warning to our athletes not to look too American. Is sochi safe? What if terror strikes? This morning, Martha Raddatz with the breaking details. Then make or break moment -- Mr. Speaker, the president of the United States. Stage is set for president Obama's state of the union. Powerhouse roundtable takes it on. Plus, shocking scandal. How lavish tastes brought down a power couple. Clinton's cover making waves. And Mitt Romney -- I can't believe you're going to lose. Stealing the sundance spotlight. All right here this Sunday morning. Hello, I'm Jonathan Karl. Great to have you with us. Much to cover. Including later, white house press secretary jay carney. We go head-to-head every day in the white house briefing room. Occasionally it gets a little heated. These memos say at the end of the day we are all stuck in the same queue because we have to go through the same portals. Jon, I get did, but the person who calls isn't the one who continues to wait after the paper application is filled. We'll see what happens with jay joining us shortly for his first Sunday show interview. But we begin with an olympic alert. New warnings about security in sochi. Straight to Martha Raddatz from the middle east. Reporter: Good morning, Jon. With opening ceremonies only 12 days away, Russia, and indeed, the world, are on high alert. The U.S. State department issued a new travel advisory Friday noting the possible presence of so-called black widow suicide bombers in sochi. It followed new threats this week vowing attacks on the games with the potential female suicide bombers still at large. Retired lieutenant general Michael Barbaro who led efforts to prevent terrorist bomb attacks explained the tough task facing Russian authorities. They have to try to defeat the toughest ied challenge there is. The suicide bomber in a crowd. No silver bullet, no technology, some facial recognition, body scanning. But it's not full-proof. Reporter: Some olympians are taking no chances. One U.S. Speed skater advising his family not to make the trip to sochi. He wanted us to stay home so that he wouldn't have to worry about us. One less thing to be concerned about. Reporter: Diplomatic security agents will accompany U.S. Athletes to all events. And the U.S. Olympic committee warned athletes not to wear U.S. Gear outside olympic venues to avoid being targeted. The only thing I said to the family was bring a jacket that doesn't scream America. Reporter: And while Russia takes the lead on securing sochi, the U.S. Has repeatedly offered its assistance. FBI agents will be on the ground during the games, and two U.S. Navy ships will be in the nearby black sea. Whatever we can do, we want to do to help. Reporter: But one informal request by Russia's top general to joint chiefs chairman martin Dempsey for American roadside bomb jamming technology may go unheeded. As far as jamming technology, we're not going to share that. Reporter: Why not? Because it's very closely held. If you understood it, you could defeat it. Reporter: The key to stopping a terror attack is intelligence. Russia, the U.S. And others are sharing whatever possible. But like anything else, it is not perfect.