What have past Republican presidents said about tariffs?

Tariff threats voiced by President-elect Donald Trump this week rippled through global stocks and triggered warnings from U.S. retail executives about the risk of higher prices.

Former President George W. Bush, who congratulated Trump a day after the election, has not commented on Trump's remarks, in keeping with a low public profile. As recently as 2021, however, Bush criticized trade barriers, lamenting the GOP under Trump as "isolationist, protectionist."

Trump's support for tariffs and skepticism toward global trade departs from previous Republican presidents spanning the past four decades.

Presidents Ronald Reagan, George W. Bush, and his father, George H.W. Bush, each venerated free trade, though in some cases they put forward policies similar to Trump's protectionist proposals.

"Trump is not talking about free trade," John Hanke, a professor of applied economics at Johns Hopkins University and a former senior economist on the Council of Economic Advisers under Reagan. "Trump's rhetoric is completely different."

In response to ABC News' request for comment, the Trump transition team said his tariff plans would boost the U.S. economy.

"In his first term, President Trump instituted tariffs against China that created jobs, spurred investment, and resulted in no inflation. President Trump will work quickly to fix and restore an economy that puts American workers by re-shoring American jobs, lowering inflation, raising real wages, lowering taxes, cutting regulations, and unshackling American energy," Trump transition spokesperson Karoline Leavitt said.

Trump late Monday said he would charge Mexico and Canada with a 25% tariff on all products coming into the United States until action is taken by those countries to stem illegal immigration and the overflow of drugs across the border.

For China, Trump said that he'd impose an additional 10% tariff on products coming to the U.S.

The declarations of trade hostility echoed vows made by Trump on the campaign trail.

Speaking at the Economic Club of Chicago in October, Trump called "tariff" the "most most beautiful word in the dictionary."

Tariffs as high as 2,000%, would safeguard key U.S. industries, such as auto manufacturing, Trump said. In the absence of tariffs, Trump added, it's "going to be the end of Michigan."

The favorable tone toward protectionist policies contrasts with rhetoric voiced by Trump's Republican predecessors.

Reagan, who served in the latter years of the Cold War in the 1980s, invoked free trade as a weapon in the fight against authoritarian adversaries abroad and perceived demagogues at home.

"Our peaceful trading partners are not our enemies; they are our allies," then-President Ronald Reagan said in 1988, after signing a free trade agreement with Canada.

"We should beware of the demagogues who are ready to declare a trade war against our friends -- weakening our economy, our national security, and the entire free world -- all while cynically waving the American flag," Reagan added.

The elder Bush, who had served as Reagan's vice president, adopted a similar posture toward trade.

As president, George H.W. Bush sought to improve trade ties with China, and he helped establish the World Trade Organization, an international body that aims to facilitate global trade through a shared set of regulations.

In the early 1990s, Bush negotiated the North American Free Trade Agreement, or NAFTA, a trade pact between the U.S., Mexico and Canada.

"Free trade throughout the Americas is an idea whose time has come," Bush said at a ceremony promoting NAFTA in December 1992.

"This century's epic struggle between totalitarianism and democracy is over. It's dead. Democracy has prevailed," he added. "Today, we see unfolding around the world a revolution of hope and courage, propelled by the aspiration of ordinary people for freedom and a better life."

The deal was ratified under Bush's successor, President Bill Clinton, a Democrat.

During his first presidential campaign in 2016, Trump sharply criticized NAFTA, which had drawn criticism for allowing manufacturers to relocate plants abroad and lay off U.S. workers.

Weeks before the 2016 presidential election, Trump described NAFTA as "the single worst trade deal ever approved in this country."

Like Reagan and his father, George W. Bush voiced support for free trade while in office. Since then, he has continued to back global commerce and oppose trade barriers.

"Since World War II, America has encouraged and benefited from the global advance of free markets, from the strength of democratic alliances, and from the advance of free societies," George W. Bush said in 2017.

"Free nations are less likely to threaten and fight each other. And free trade helped make America into a global economic power," George W. Bush added.

Despite their rhetoric, Trump's predecessors within the Republican Party put forward some policies that resembled his proposals this week.

Reagan slapped 45% tariffs on Japanese motorcycles, and 100% tariffs on some Japanese electronics, seeking to counter that nation's economic rise and bolster domestic industry. Reagan also placed an annual quota on the allowable number of imported Japanese cars.

"There was a huge gap between rhetoric and reality," Hanke, the former Reagan administration economist, told ABC News.

For his part, George W. Bush attempted to protect the U.S. steel industry by placing tariffs on some steel imports. Facing pushback from the World Trade Organization and threats of retaliation from other countries, he removed the tariffs after 18 months.