(CNSNews.com) - The Islamic terrorists who attacked Charlie Hebdo and a Jewish market in Paris last week were on the U.S. no-fly list, but many other Europeans can travel here without a visa -- and that's a problem, according to Sen. Dianne Feinstein (D-Calif.), the former chair of the Senate intelligence committee:
"It's my belief -- and I have said this publicly many times -- that the visa waiver program is the Achilles' heel of America, because you're right, Gloria. They can come back from training, they go through a visa waiver country, and they come into this country.
"Now, there are no-fly lists. There are terrorist lists. But they're in the tens of thousands and even millions, so it's difficult to ferret someone out. They -- there are stolen travel documents in large numbers that they can pick up -- pick up a false passport, et cetera.
"So, we have a big problem there. I think we need to take a look at the visa waiver program again, and see what we can do to prevent this kind of thing from happening, because I believe it will happen, if it hasn't already."
Feinstein was speaking to Gloria Borger on CNN's "State of the Union."
Rep. Michael McCaul (R-Texas), chairman of the House Homeland Security Committee, told CBS's "Face the Nation" that the U.S. no-fly lists are working -- "but you don't know what you don't know."
He said the U.S. needs to identify the people who are going over to Syria and Yemen so their travel to the U.S. and Europe can be restricted.
"And we have a visa waiver (program), free system where they can fly into the United States without even having a visa. We need to look at all sorts of the things like that."
McCaul said his committee is launching an investigation "to look at security and defense gaps that may exist as it pertains to foreign fighters."
The greatest emerging terror threat to the United States is that of foreign fighters returning from training camps in Syria or Yemen to wage attacks in their home countries, including the United States. U.S. officials are worried not only about radicalized Americans, but also about Europeans who may come here with violent intentions.
The Visa Waiver Program (VWP), created by Congress in 1986, is now administered by the Department of Homeland Security. It allows eligible citizens or nationals from 38 designated countries to travel to the United States for tourism or business -- for stays of up to 90 days -- without first obtaining a visa.
DHS also operates the Electronic System for Travel Authorization (ESTA), an automated system that determines whether people traveling under the Visa Waiver Program pose any law enforcement or security risk. Travelers must complete an ESTA application before coming to this country.
According to DHS, "ESTA adds another layer of security that allows DHS to determine, in advance of travel, whether an individual is eligible to travel to the United States under the VWP and whether such travel poses a law enforcement or security risk."
France joined the Visa Waiver Program in 1989.