Intelligence officials tell NBC News that Canadian authorities have heard would-be terrorists discussing potential ISIS-inspired "knife and gun" attacks against U.S. and Canadian targets inside Canada.

While intelligence officials say some of the discussions raise the possibility of attacks on U.S. citizens and other U.S. and Western targets in Canada, they have not picked up talk of anyone crossing the border into the U.S. to stage attacks. They also stressed that the possible attacks were at the "aspirational" stage.