Threat? What Threat?

If we have a good reason to ground a flight for security reasons, then why not share at least some of our intelligence with a trusted friend? If we have a good reason, then why deny that a flight was cancelled because of our actions?
The U.S. government shared threat information with the Mexican government, which canceled a scheduled U.S.-bound flight from Mexico because of security concerns.

Agustin Gutierrez, Mexico's presidential spokesman, said Mexico did not receive convincing information for the cancellation.

"The question is what threat?" Gutierrez said. "This question must be answered by Homeland Security. If we are going to have a good climate of cooperation, the least that we can hope for are reasons."

Gutierrez also said the cancellation came after United States authorities said they would refuse to allow the plane to land, but Homeland Security Department spokesman Brian Roehrkasse denied that.