Michael Downing, who recently retired as chief of the Los Angeles Police Department's counterterrorism unit, spent years building bridges to local Muslim communities.
Now he sees evidence that President Donald Trump's early counterterrorism initiatives have seriously damaged those ties — making America less safe in the process.
"The outcome from some of the federal policies has been fright and anxiety," Downing told NBC News. "I've had Muslims leaders call me and say, 'Do you think it's really possible that we're going to go to internment camps?'"
Trump's embrace of terms that directly link extremism to Islam, and his efforts to impose a travel ban on residents of a handful of majority Muslim countries, represent a marked departure in tone from his two most recent predecessors, who sought to avoid an impression that the West was at war with the world's 1.6 billion Muslims.
Downing and other law enforcement officials told NBC News that Muslim-Americans are becoming reluctant to cooperate with a federal government they increasingly mistrust, and may stop providing crucial tips about potential terrorists.
The Take, an NBC News podcast, looks into the real world impact of the Trump administration's rhetoric linking extremism to Islam.
Our guest is NBC News National Security Reporter Ken Dilanian.
"If we lose that trust and if they look at us with eyes of suspicion, then some are going to go underground," Downing said. "I think there is evidence already of that happening."
Extremists overseas, meanwhile, are citing Trump's rhetoric as evidence that American hates Islam.
"I think he is good for us," a Canadian ISIS fighter told Amarnath Amarasingham, a terrorism expert at George Washington University. "We needed someone like him, who is direct."
So far, the substance of Trump's counterterrorism policies has not been dramatically different than Obama's. Trump is contemplating loosening restrictions on drone strikes, and he agreed to a military escalation against al Qaeda in Yemen. But he has largely followed the Obama strategy against ISIS in Iraq and Syria.
It's the rhetoric that is starkly different.
"The president has spoken. The threat we face is from radical Islamic terrorism. If you have a problem with any part of that definition, then you are in denial," Sebastian Gorka, a special assistant to the president who has been involved in the new policies, told NBC News