The Gold Star dad who forcefully criticized President Donald Trump’s rhetoric on Muslims announced Monday that he was canceling a trip to Toronto because his “travel privileges” are under review.

Khizr Khan, a Muslim American whose son, U.S. Army Capt. Humayun Khan, was killed by a bomb in Iraq in 2004, was catapulted into the national spotlight after he whipped out a pocket copy of the U.S. constitution during his Democratic National Convention speech. His moving tribute to his son quickly made him a target for conservatives, who tried to paint the Pakistani immigrant as an Islamic extremist.

The Harvard-trained lawyer shuttered his firm and became an outspoken activist. But what exactly happened to force Khan to cancel his Toronto speech is unclear, as is the status of Khan’s ability to travel.

CTV’s Rosa Hwang broke the news Monday afternoon, tweeting that Khan had canceled his planned appearance over a review of his “travel privileges”—a choice of phrase that immediately incited speculation on Twitter. Hwang’s source was Ramsay Talks, a popular Toronto lecture organization, which announced Khan’s cancellation in a posted statement.

“Late Sunday evening Khizr Khan, an American citizen for over 30 years, was notified that his travel privileges are being reviewed,” the statement read. “As a consequence, Mr. Khan will not be traveling to Toronto on March 7th to speak about tolerance, understanding, unity, and the rule of law.”

Ramsay Talks did not return The Daily Beast’s request for comment.

Instead, The Daily Beast called Customs and Border Patrol. CBP spokespeople did not explain what happened to Khan, but brushed away the notion that the father was told he could not go to Canada.

“We don’t do that. We’re not going to review… no, no,” Janice Mosher from U.S. Customs and Border Protection public affairs told The Daily Beast. “It’s not something we do.”

Mosher suggested that the Transportation Security Administration might have more information.

But a TSA spokesman directed The Daily Beast back to CBP. “That’s their swim lane,” Brian McNeal of the TSA said.

People for the American Way, where Khan is a board member, declined to comment as well. Attorneys at Dulles Justice, the immigration group Khan recently visited at the D.C.-area airport, also said they had no information to share.

A different CBP spokesperson, however, later replied to The Daily Beast by email, saying the agency does not give travelers a heads-up ahead of overseas trips. The agency does not discuss individual cases, he added.

Then, unprompted, he brought up the expedited screening program Global Entry.

“With respect to Global Entry or trusted traveler membership, CBP’s engagement is about the status of membership in the program, not any particular travel itself,” he said. “Of course, any U.S. citizen with a passport may travel without trusted traveler status. All individuals are subject to inspection departing or upon arrival to the United States.”

Mic reported last month that some Muslim Americans have had their Global Entry status revoked without explanation after Trump took office.

The Daily Beast reached out to Khan to ask whether the cancellation was regarding a Global Entry or Pre Check status.

“Thank you—no comments,” he wrote back.