President Trump employed several aggressive tactics to pressure Canada and Mexico into renegotiating NAFTA, ultimately resulting in the new United States-Mexico-Canada Agreement (USMCA)14. Here's how he forced concessions:

1. Threats of withdrawal: Trump repeatedly threatened to pull the United States out of NAFTA entirely if a new deal couldn't be reached1. This created urgency for Canada and Mexico to negotiate, as the economic consequences of a U.S. withdrawal would have been severe for both countries.

2. Imposing tariffs: In June 2018, Trump imposed tariffs on Canadian steel and aluminum imports, citing national security concerns1. This move significantly increased pressure on Canada to make concessions in the negotiations.

3. Divide and conquer strategy: Trump initially reached a bilateral agreement with Mexico, isolating Canada and forcing it to negotiate separately1. This tactic weakened Canada's bargaining position.

4. Extreme demands: The Trump administration made several extreme demands during negotiations, such as proposing a "sunset clause" that would have NAFTA expire after five years unless explicitly renewed1. While not all of these demands were met, they set a high bar for negotiations.

5. Public criticism: Trump used social media and public statements to criticize Canadian Prime Minister Justin Trudeau, calling him "meek and mild" and increasing political pressure1.

6. Leveraging economic power: The U.S., being the largest economy in North America, used its economic clout to push for more favorable terms in areas such as automotive rules of origin and access to Canada's protected dairy market46.

7. Tying trade to national security: Trump framed the trade negotiations as a matter of national security, particularly regarding the flow of illegal drugs and immigration5. This allowed him to justify more aggressive measures.

While these tactics did lead to a renegotiated agreement, it's worth noting that many of the changes in the USMCA were relatively modest compared to the original NAFTA6. Additionally, the aggressive approach strained relationships with long-standing allies and trading partners1.