More than 24 hours after organizers claimed Monday that Khizr Khan, the Gold Star father widely known for his criticisms of President Trump, had canceled an event in Canada after finding out his “travel privileges are being reviewed,” there’s still no concrete evidence to substantiate the claim.

The statement quickly ricocheted around social media, despite sparkingskepticism among journalists. But the circumstances surrounding the event’s cancellation remain murky. On Tuesday, The Washington Post reported that Bob Ramsay of Ramsay Talks said he was not aware of “exactly who conducted the review,” but indicated that based on his communication with Khan, “it was certainly U.S. authorities.”

William Stock, an immigration lawyer based in Philadelphia, professed his puzzlement about Khan’s account. “Mr. Khan has not provided any details that would allow me to figure out what the heck he’s talking about,” said Stock.

He added that he was surprised by the report, in part because it’s not clear what “travel privileges” is referring to. “The use of that term makes no sense,” said Stock, who is the president of the American Immigration Lawyers Association. “International travel has generally been seen as a right for U.S. citizens, not a privilege.”

The travel plans of the average American citizen would, of course, not generate the intense media coverage Khan has received. But Khan, the father of a slain Muslim American soldier, went from relative obscurity to become a high-profile political figure and Trump critic last summer, and he has remained critical of the president since.

Khan first came to prominence when he rebuked Trump at the Democratic National Convention, questioning whether the then-Republican presidential candidate had ever read the U.S. Constitution and accusing him of smearing “the character of Muslims.” Trump later responded in a statement that although he feels “for the loss of his son … Mr. Khan, who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things.”

The intensity of the coverage may have also had to do with timing: The notice of cancellation came on Monday, the same day the Trump administration issued a revised version of its travel ban. The original version of the ban, which was issued in January, prohibited travelers from seven Muslim-majority nations. Khan himself had been critical of its first iteration, including in an interview with The Toronto Star last week.

But until Khan himself chooses to clarify the claims made in his name, it may be impossible to tell what actually led to the cancellation of the Toronto event.