Washington (CNN)The waiver program that allows citizens from some countries to enter the United States for up to 90 days without a visa is "the Achilles heel of America," Sen. Dianne Feinstein said on Sunday.
Feinstein: Visa program is 'Achilles heel'
The California Democrat and former Senate Intelligence Committee chairwoman's comments, on CNN's "State of the Union," come on the heels of the Paris attack on the satirical newspaper Charlie Hebdo.
Feinstein noted that the suspects in the attack were French citizens -- and people from France can enter the United States without visas. The suspects were on a no-fly list, but she said they could obtain a false passport or find some other way to go unnoticed.
She said other terrorists will likely do just that, if they haven't already.
"They can come back from training, they go through a visa waiver country, and they come into this country," Feinstein said. "We have a big problem here."
Feinstein has long been a critic of the program. She's called it a potential avenue for terrorists to enter the United States since President George W. Bush's administration expanded the list of countries that are included in the waiver program.
She also said there are "sleeper cells" in the U.S. that could lead to similar attacks domestically.
"I think there are sleeper cells, not only in France, but certainly in other countries, and, yes, even in our own," Feinstein said. "So I think this calls for vigilance. It calls for seeing that the national security organizations of our country -- the intelligence community -- is funded fully, is directed ably, is cooperating with ... British intelligence, French intelligence, German intelligence, as we do."