The US is grounding some Canadian NHL team charter flights and Transport Minister John Baird is threatening to retaliate against American teams, Canwest News Service reported last week. Last month, the US changed a rule that allowed Canadian charters to fly between US cities. The change could also affect musicians and other performers. Mr. Baird says he's directed the Canadian Transportation Agency to launch a formal inquiry. The next step is to "prohibit charter flights by US carriers under season-long contracts with professional sports teams with multiple stops in Canada," Mr. Baird said.