On Sunday, President Donald Trump declared on Twitter that the tariffs already imposed on Chinese goods “are partially responsible for our great economic results” and announced that they would increase from 10% to 25% on Friday.

“The Tariffs paid to the USA have had little impact on product cost, mostly borne by China,” Trump continued. “The Trade Deal with China continues, but too slowly, as they attempt to renegotiate. No!”

But is it really true that the tariffs haven’t had a negative impact on the American people?

Treasury Secretary Steven Mnuchin said Monday that “there’s no question that some of the trade policies helped in the GDP number.”

But the tariffs announcement already sent stocks reeling on Monday. The Dow fell by nearly 471 points in early trading before closing down 66 points, or 0.3%. The S&P 500 and Nasdaq fell about 0.5% by closing.

Chad Brown, senior fellow at the Peterson Institute for International Economics tweeted his disagreement with Trump’s assertions on Sunday.

“The economic evidence to date on this is exactly the opposite of Trump’s statement,” he wrote. “The impact of the 2018 tariffs has been passed on to US consumers in the form of higher prices. China is NOT bearing the burden of Trump’s tariffs…”

The precise impact beyond the stock market remains to be seen: it will depend in part on how China responds to the threat by the Trump administration. Yet research undertaken in the months since the first tariffs were imposed show that several industries are already beginning to feel the crunch.

Steel and aluminum tariffs have increased production costs for manufacturers, which translates into higher prices for consumers. The Peterson Institute for International Economics found that tariffs last year increased the price of steel products by nearly 9%, pushing up costs for steel users by $5.6 billion.

Tariffs have also driven up the cost of washing machines. A study by the University of Chicago’s Becker Friedman Institute of Economics found that consumers are now paying 12% more for washing machines, or the equivalent of $1.5 billion a year.

Chinese tariffs on U.S. agricultural exports have also negatively impacted American farmers.

These tariffs have had a particularly acute effect on soybean farmers, as China, the world’s biggest soybean importer, cut off purchases from the U.S. last year. Although the U.S. reached a truce with China earlier this year, it wasn’t enough to stop U.S. soybean exports to China from dropping to their lowest level since 2008, causing prices to plummet and hurting the farmers who sought to sell their harvests.

For the most part, the impact of these tariffs have been felt most deeply by American businesses and not individual Americans. But if Trump makes good on his promise to levy a 25% tariff, that could begin to change, pressuring more businesses to pass on these added costs to the consumer.

But it may not even be the tariffs themselves that could have the greatest effect. If a tit-for-tat arises once again between the U.S. and China, spurring a full-blown trade war, it wouldn’t just be a handful of industries and some consumers that are debilitated: the IMF has warned that it could weaken the entire global economy.

But it’s not time to panic just yet. China confirmed on Tuesday that its economy czar will go ahead with plans to come to Washington, D.C., for trade talks with the Trump administration, meaning a peaceful resolution to the ongoing negotiations is still possible.