The United States has said it would increase security at overseas airports with nonstop flights to the country amid terror fears.
The new measures would be required at airports in Europe, Africa and the Middle East.
The US Department of Homeland Security did not specify what has triggered the extra security precautions.
Washington has legal authority to enforce new security requirements on foreign governments because the flights go directly to the United States.
The new measures would involve additional inspections of passengers’ shoes and property.
US officials have said there are concerns that al Qaeda terrorists in Syria and Yemen were developing bombs that could be smuggled onto planes.