-- Beginning today, passengers booked on U.S.-bound international flights with at least four different airlines will be required to complete a short, verbal security interview before they board, sources told ABC News.
The interviews will be conducted during document check, check-in or at the gate, the airlines told ABC.
Like the electronics screening requirement, the enhanced passenger screening requirements affect 280 airports in 105 countries running about 2,000 flights, with about 325,000 passengers per day.
Though many airlines opted to do interviews, some may meet the requirements in other ways.
"We cannot play international whack-a-mole with each new threat," Kelly said told reporters in June. "Instead, we must put in place new measures across the board to keep the traveling public safe and make it harder for terrorists to succeed."
"Security adjustments rooted in legitimate concerns are a fact of life for travelers," U.S. Travel Association Executive Vice President Jonathan Grella said in a statement today, adding that all changes in security posture should be "clearly communicated," "continually reassessed" and "tailored to specific vulnerabilities."
"Legitimate business and leisure travelers are as welcome as ever in the United States," he said.
ABC News' Jeffrey Cook contributed to this report