As Canada, the U.S. and Mexico work to hammer out a revised North American Free Trade Agreement, former prime minister Brian Mulroney said “only a fool” would try to upend the benefits of free trade.

Mulroney has been a champion of free trade, having signed the Canada-U.S. Free Trade Agreement and NAFTA while Prime Minister from 1984-1993, and said countries can look to history to realize the economic benefits of more liberalized trade.

“The [Canada-U.S.] free trade agreement proved to be precisely the jolt out of complacency our firms needed,” he said during a speech at the Oakville Chamber of Commerce in Oakville, Ontario. “The economic results were even more positive than anyone in the government or anyone else envisioned at the time.”

Mulroney said the surge in trade led to millions of new jobs being created and record prosperity for all countries involved.

“Only a fool would seek to upend this majestic reality and accomplishment.”

Mulroney also said that “leaders must have vision and must find the courage to fight for the policies that will give that vision life.” Governing isn’t about “easy headlines in 10 days.”

Tensions in current NAFTA renegotiations have been boiling over into the public eye recently, with Foreign Affairs Minister Chrystia Freeland making it clear the trio remain far apart on certain issues and U.S. Trade Representative Robert Lighthizer saying he was “surprised and disappointed” by his counterparts for their “resistance to change.”

The U.S. has been accused of putting forth aggressive NAFTA proposals viewed as protectionist or, according to Freeland, run counter to World Trade Organization rules.

But Canada has its own list of demands, including keeping dispute resolution mechanisms in the agreement and maintaining Canada’s supply management for the dairy sector.

“I’m persuaded the highly talented and capable team put together by Prime Minister Trudeau will do a top flight job for our country,” Mulroney said.

“History has little time for the marginal roles played by the carpers and complainers and less for their opinions. History tends to focus on the builders, the deciders, the leaders in education, healthcare, science, business, the arts, as well as politics.”