As ISIS threatens to strike inside the U.S., airlines are keeping their schedules of flights from the U.S. to Paris and back, but U.S. authorities are intensively scrutinizing passenger lists on inbound flights.
Intelligence officials say that U.S. terror databases contain more than 2,700 names with connections to France, and NBC News has learned that 801 of them are considered potential "foreign fighters" who might try to join ISIS in Syria. Authorities are paying particular attention to their attempts to travel.
Five of the individuals on the potential foreign fighter list have traveled or tried to travel to or from France in the past three months.
Two of the five travelers flew from Paris to the U.S. in August and October, and a dual U.S./Pakistani citizen traveled from New York to Paris and back in October.
A dual Algerian/French national tried to fly from Paris to Canada earlier this month, but was denied boarding in France. A Syrian national tried to depart from Paris in August, but the outcome of his attempted travel was not known to U.S. officials.
There was no indication that the travelers were involved in terror plotting.
After Friday's massacre in Paris, U.S. officials received 20 single fingerprint images from French authorities, but got no matches from U.S. government databases.