The U-S government says it's reviewing how Ontario and other provinces sell wine in local stores.
American trade officials have complained that Canadian wine sales unfairly advantage local products over American imports.
Under NAFTA, the Canadian wine industry was allowed to grandfather trade protections to support domestic wines, but had to open up the Canadian market for more American vintages.
Canadian wine associations say the small size of domestic wine production, in comparison with U-S output, could leave them at a disadvantage