A gate area at Fort Lauderdale-Hollywood International Airport is crowded with travelers awaiting Delta flight 1420 to Atlanta Saturday, March 14, 2020.

The Trump administration is weighing "all options" to curb the coronavirus outbreak in the U.S., including an outright halt to domestic air travel, a senior official said Sunday.

Such a drastic step hasn't been taken since the Sept. 11, 2001 attacks, and it would raise questions about U.S. airlines' chances for survival without government support.

"We continue to look at all options and all options remain on the table," said Chad Wolf, acting secretary of the Department of Homeland Security in a press briefing when asked about the possibility. He said the administration is following guidance from the Centers for Disease Control and Prevention.

The Trump administration last week instituted a broad ban on foreign visitors from 26 European countries, which will be expanded to the U.K. and Ireland overnight.

The sudden change in rules sparked chaos at some of the country's largest airports, including Chicago's O'Hare, where returning Americans faced hours-long lines in cramped arrivals halls.

Wolf called those conditions "unacceptable" and that conditions have improved with staffing changes at the airports.