New tariffs imposed by the US on Canadian imports have taken effect, affecting roughly $20 billion in goods. These tariffs, set at 50%, will impact American companies and consumers, raising prices on various products. Canada's prime minister has vowed to retaliate with similar measures, starting in September.

The retaliatory tariffs will be imposed "dollar for dollar", according to the prime minister. Ontario's premier has also spoken out against the US trade policies, suggesting that a former US president would be displeased with the current approach.

Further details on the trade dispute and its potential consequences are available from the source. The situation continues to unfold, with potential impacts on trade between the two countries.