Only 19 U.S. airports have received sophisticated imaging machines that can detect explosives hidden in clothing.

Security experts say the scanners may be the best defense in stopping attacks such as an attempt to bomb a Detroit-bound aircraft Christmas Day.

The Transportation Security Administration wants to install more of the devices, known as whole-body imaging scanners, but the agency has met resistance from civil liberties groups, passengers and some members of Congress.

Read the rest at NBC DFW.

Following are a list of new measures, as reported by some airlines and passengers who have traveled in recent days. The Transportation Security Administration gave only limited details of new measures on its website, but several airlines said they had been ordered by the United States to implement the new policy:

- On many international flights destined for the United States, passengers are being limited to one personal carry-on bag and are asked to check other bags and packages.

Read the rest of the list at Reuters.