The United States demanded more careful screening for people who are citizens of, or are flying from, 14 nations deemed security risks. But enforcement of the U.S. rules appeared spotty.

"Everything is the same. There is no extra security," said an aviation official in Lebanon, one of the countries on the list. The official spoke on condition of anonymity because he was not authorized to speak publicly.

The Obama administration ordered the changes after what authorities say was a failed attempt by a Nigerian man to blow up a jetliner bound from Amsterdam to Detroit on Christmas Day.

The U.S. Transportation Security Administration said the enhanced screening techniques would include full-body pat-downs, searches of carry-on bags, full-body scanning and explosive-detection technology.