Canadian Prime Minister Mark Carney has rejected the latest US trade offer after last-ditch trade talks between the two countries collapsed, warning that Ottawa will retaliate with new tariffs targeting sectors including steel and dairy. Carney said the measures would come into effect on September 8.

Negotiations between the U.S. and Canada broke down late Friday and tariffs went into effect early Saturday morning.

Canadian Prime Minister Mark Carney vows to retaliate, says his country recognized that 'America has changed' and that the two countries would 'not return to our old relationship'

WASHINGTON/OTTAWA -- The United States and Canada failed to reach a trade deal on Friday, and the White House said that it would impose 50-percent tariffs on certain imports from…