The federal government will unveil proposed retaliatory tariffs on an initial round of American imports Monday if incoming U.S. president Donald Trump uses his inauguration to immediately proceed with threatened levies on Canada.

A government source familiar with Ottawa’s plans says if this happens, Prime Minister Justin Trudeau would announce a rapid consultation period – possibly two weeks – on a first round of tariffs that would cover approximately $37-billion of U.S. imports, with implementation to follow immediately after.

These would be the least painful countertariffs, the source said, because they would cause the least economic damage to Canadians.

The Globe and Mail is not identifying the source because they are not authorized to publicly discuss these matters.