AS a security professional with counterterrorism experience, I understand the threat posed by religious extremism. As a former Secret Service agent who has taught about radicalization to the C.I.A., the N.S.A., the Department of Homeland Security and the United States military, I have seen up close how Muslims are treated in European society, especially French society.

I was a Secret Service agent on the 2004 visit to France by George W. Bush, who was then president, and my responsibilities included obtaining cars, hotel rooms, cellphones and translators for a small army of agents who would arrive in advance of his trip. Two weeks before, I ordered 20 cars and 20 French drivers for members of the Secret Service advance team. The cars and drivers lined up in front of a five-star Paris hotel where members of the Secret Service, United States military and White House staff were staying.

All of the drivers were dressed professionally in suits, but only one was stopped and questioned each day by the French police. His name was Ahmad and he was clean-shaven, about 25 years old, born in France and of Moroccan descent. Almost daily I would be summoned to the outside of the hotel to verify that he was part of our team. After a few days of this, I offered to contact the police and try to stop the constant and redundant checks. He smirked and told me, “You cannot change French society.”

What seemed most strange to me was that Ahmad never complained about the police intrusion and actually accepted it as a fact of life. When I drove with Ahmad through the streets of Paris, he was stopped three times by police officers at roundabouts and traffic lights. Each time he produced identification, explained the car was not his and that he worked for a limousine service. Within minutes the police let him go, and they were always professional and polite. But while he didn’t complain, Ahmad felt humiliated, like an outsider. Not truly French.