Canada is set to impose retaliatory tariffs of up to 50% on hundreds of U.S. products beginning just after midnight Tuesday, marking a significant escalation in the trade dispute between the longtime allies.

The new levies will affect a wide range of American goods, including aluminum foil, raincoats and cheese, as Ottawa responds to a recent round of U.S. tariffs.

Canadian officials said the measures will target approximately $20 billion worth of U.S. imports, roughly matching the value of the latest American tariffs on Canadian goods.

Based on 2025 U.S. Census Bureau trade data, the targeted products represent nearly 6% of annual U.S. exports to Canada.

The escalating dispute has also raised concerns among U.S. lawmakers representing states that share a border with Canada. Maine Republican Senator Susan Collins is among those warning that higher tariffs could increase costs for consumers and hurt businesses that depend on cross-border trade.

The latest measures follow the collapse of trade negotiations between Washington and Ottawa last month. After a new round of U.S. tariffs took effect, Canadian officials announced plans for matching retaliatory duties beginning in the second week of September.

The move further intensifies the tit-for-tat trade conflict between two economies with deeply integrated supply chains and could prompt additional action from the Trump administration.