OTTAWA — Canada on Tuesday announced counter-tariffs on U.S. goods ranging between 15 percent and 50 percent, intensifying the trade war between the historically close allies. Ottawa's retaliation takes effect September 8, a timeframe earlier outlined by Prime Minister Mark Carney after U.S. President Donald Trump's 50-percent duties on Canadian products came into place Saturday. In detailing Ottawa's response, officials said Tuesday that its duties will match U.S. levels. These impact industries like steel, dairy and electronics. Canada's government also announced a $5.4 billion (CA$7.5 billion) aid package for impacted firms and workers. "This is an unprecedented challenge imposed on Canada. But Canada will meet the moment," Canada's Finance Minister Francois-Philippe Champagne said. "I think what Canadians can see this morning is that we stand united. We stand united in our response," he added. Tit-for-tat? The steep U.S. tariffs hit about $20 billion in Canadian goods — about 5.5 percent of its exports to the United States — after trade negotiations collapsed at the eleventh hour.