. Passengers on those flights "may notice enhanced security and random screening measures throughout the passenger check-in and boarding process, including the use of explosives trace detection,
advanced imaging technology, canine teams or pat downs, among other security measures," according to a Department of Homeland Security statement. Expanded use of such measures began after last year's attempted Christmas Day attack, with a particular focus on passengers from 14 nations deemed by the United States as state sponsors of terrorism or other countries of interest. In late January,
Napolitano told senatorsthat "over half of [inbound] passengers from all other countries" also were being subjected to enhanced screening.