Expressing regret over the Indian Ambassador to Washington Meera Shanker, being pulled out of an airport security line and patted down, the US today promised to ensure that such incidents do not recur. The Obama administration has regretted the humiliating incident that took place on December 4 at the Jackson-Evers International Airport when sari-clad Meera Shankar was about to board a flight to Baltimore after attending the Mississippi State University's programme.The US Secretary of State Hillary Clinton told reporters in Washington that they are concerned about it and will be looking into the incident to determine on what happened and what could be done to prevent such incidents in the future. Indian Embassy spokesman Virander Paul said, the US State Department has reached out to the Ambassador and has regretted what all had happened. He said, the Embassy is in touch with the State Department on this issue. External Affairs Minister S M Krishna had called the pat-down of Meera Shankar as unacceptable.