"Identifying so-called self-radicalization is unquestionably a tough problem," Clapper said. "We are in dialogue with the Muslim community. And that is going to be a source of advice, counsel, and wisdom, as well as hopefully alerting us to those among their number who are professing radical views."
While the Times Square bomb attempt and the Christmas Day plot were both extremely close calls, Brennan claimed that both scenarios actually showed strides on the part of U.S. officials in securing the country.
"Neither one of those attacks were successful," he said. "People may attribute it to luck, but I think it's because of the pressure that we as the U.S. government have put on the terrorist groups over the past decade."
The group did acknowledge that the U.S. still has plenty of work to do, particularly overseas where a radical message often takes root and terrorists can find sanctuary.
"Terrorists hide in certain places. They're operating and training in certain areas, and we need to continue to work with our foreign counterparts to make sure that they're doing their best to root these individuals out," he said. "We have to continue to adapt, continue to be flexible, and to continue anticipating what the terrorists are thinking themselves."
Sawyer asked about recent comments from Michael Leiter at the National Counterterrorism Agency, asserting that not all attacks can be stopped and some innocent lives will inevitably be lost.
"I think Mike Leiter was correct," Napolitano said. "You cannot hermetically seal the United States."
"We're not going to bat 1,000 necessarily. We can't guarantee that," said Clapper. "But we're certainly doing everything we can to ensure that we do thwart any kind of an attack."
"What I say to the American people is that ... thousands of people are working 24/7, 364 [sic] days a year to keep the American people safe," said Napolitano.
"There are evil people in the world who are trying to do us harm," said Brennan, "but this government has come an awfully long way."
Susie Banikarim, Margaret Aro and Rick Klein contributed this this report.