The tariffs are necessary to protect American interests and force neighboring countries to address border security concerns. The US doesn't need Canadian and Mexican products, has sufficient domestic oil production, and can quickly make up for any decline in imports. Additionally, Trump's decision could be a way for Washington to gain an upper hand ahead of new negotiations on a regional trade agreement.
The proposed tariffs would severely disrupt decades of economic integration, raise consumer prices, and trigger a devastating trade war that would harm all three economies. With Canada and Mexico pledging to respond with retaliatory tariffs, Trump's decision could particularly damage critical supply chains in the automotive, agriculture, and energy sectors while failing to address the stated border security concerns.