President Donald Trump imposed the steepest American tariffs in a century as he steps up his campaign to reshape the global economy, sparking threats of retaliation and a selloff in markets around the world.Trump announced on Wednesday he will apply at least a 10% tariff on all exporters to the US, with even higher duties on some 60 nations, to counter large trade imbalances with the US. That includes some of the country’s biggest trading partners, such as China — which now faces a tariff of well above 50% on many goods — as well as the European Union, Japan and Vietnam.“For years, hard-working American citizens were forced to sit on the sidelines as other nations got rich and powerful, much of it at our expense,” Trump said during an event in the White House Rose Garden to unveil the so-called reciprocal tariffs. “Now it’s our turn to prosper.”The move marks a dramatic follow-through on Trump’s long-held trade grievances, one that risks triggering retaliation from other countries and upends calculations for businesses and consumers at home. China and the EU, America’s largest trading partner, both said they were preparing to take countermeasures in response.The US president has embraced tariffs as a tool to assert US power, revive manufacturing at home and extract geopolitical concessions — counter to the decades-old consensus that lower trade barriers help to foster ties among nations and prevent conflicts. Economists say the near-term result of his measures will likely be higher US prices and slower growth, or perhaps even a recession.“There is still much uncertainty — and room for negotiation,” Maeva Cousin and Rana Sajedi of Bloomberg Economics wrote in a research note. “This could create sizeable stagflation risks for the US economy, and pose major challenges to partners reliant on US demand.”Global financial markets were hit by a sweeping selloff after Trump’s announcement, with US equity futures slumping as much as 4%. Stocks linked to global trade bore the brunt, with Apple Inc down about 7%.Meanwhile, gold hit an all-time high and the Japanese yen, traditionally a haven, soared. Ten-year Treasury yields fell toward the closely watched 4% level, their lowest since October, and a Bloomberg gauge of the dollar tumbled more than 1%.Less than three months after returning to the White House, Trump has already erected trade barriers that are bigger by some measures than those imposed in the notoriously protectionist 1930s. Bloomberg Economics calculates that the effective tax rate the US now charges on more than $3tn of imported goods may climb to around 23% — higher than any point in more than a century.A statement published Wednesday by the US Trade Representative explained the Trump administration calculated its raft of new tariffs primarily based on existing trade balances. Countries running a trade surplus with the US faced a flat 10% rate regardless, as did nations where trade was roughly even.There’s a small difference in the tariff rates first announced by Trump and more than a dozen of those listed in the annex that accompanied the White House executive order. For countries like South Korea, Myanmar, Pakistan and India, the rates in the annex are about 1 percentage point higher than the initial announcement.The 10% baseline charge on everyone takes effect after midnight Saturday. The higher duties on targeted countries — which replace, rather than add on top of the 10% rate — are due to kick in on April 9, the White House said.For now, the new measures don’t include Canada and Mexico, which are embroiled in a separate on-and-off tariff dispute with the US. They also won’t apply to some products that are subject to separate duties tied to so-called Section 232 investigations such as autos, semiconductors and lumber.The reciprocal tariffs were “much worse than we feared,” said Mary Lovely, a senior fellow at the Peterson Institute for International Economics. There’ll be “huge implications for rerouting of trade,” she said.The president, who’s sought to frame his trade plans as a boost for his blue-collar voters, was joined in the Rose Garden by union members and workers from various industries — including a retired autoworker who spoke on stage. Later, Trump brandished large boards during his 48-minute address to display each nation’s new rate.China, the top US economic rival and chief target of Trump’s first-term trade war, is in his crosshairs again.The country will get charged a 34% reciprocal tariff rate, according to the White House documents — stacked on top of 20% duties Trump already imposed this year tied to fentanyl trafficking. That means many Chinese imports face tariffs well above 50% — high enough to wipe out most US-China trade by the end of this decade, based on estimates by Bloomberg Economics.The latest measures bring average US tariffs on all Chinese products to as high as 65%, according to economists. That rate includes existing tariffs from the first Trump term that were maintained by the Biden administration.