where government forces have launched their biggest campaign to get background they've lost to Sunni militants. The two sides waged a fierce fight over tikrit, hometown of the former dictator saddam... See More
where government forces have launched their biggest campaign to get background they've lost to Sunni militants. The two sides waged a fierce fight over tikrit, hometown of the former dictator saddam hussein. The militants appear to still hold the city center. While the Iraqi army is pressing towards them. But the chaos in that region has the white house and homeland security officials on alert that it may reach our shores. ABC's chief justice correspondent Pierre Thomas reports in tonight. Reporter: As those armed U.S. Drones fly over Baghdad, it's becoming painfully clear that what's happening in Iraq and Syria could threaten the American homeland. This week, senators were noticeably shaken after a classified briefing about the threat. One thing I learned from this briefing, our homeland is at risk. Reporter: Of urgent concern? Radicals in Syria, some with european and U.S. Passports, who may try to get on commercial planes carrying a new generation of bombs disguised as everyday carry-on items -- toothpaste, clothing, cosmetics -- designed to slip through airport security. What's happening in Syria and Iraq is the latest indication that the Al Qaeda brand is alive and well, popping up around the globe. They're gaining strength, aren't they? Well, they're gaining strength in some places. But we've also gotten a lot better at protecting ourselves. Reporter: No specific threat has been identified, but as we head towards the fourth of July holiday, U.S. Authorities will be working hard, keeping all the scary information in mind. Rebecca? Clearly no one wants to take any chances there. Pierre Thomas, thank you. And you can see much more of George's interview with the president tomorrow morning on "This week."
This transcript has been automatically generated and may not be 100% accurate.