LONDON, U.K.: American consumers and businesses could soon face the highest overall tariff burden in more than a century, according to the International Chamber of Commerce (ICC), following President Donald Trump's latest round of import levies.

The ICC now estimates the effective U.S. tariff rate may exceed 20 percent, surpassing levels not seen since the early 1900s. Current rates are already near 16 percent—their highest since the 1930s.

The ICC, which represents 45 million companies across more than 170 countries, views the new measures as a deliberate stress test for financial market tolerance.

"Our view right now, based on what we've seen over the past few days, is the Administration is very much set on achieving the highest possible effective tariff rate for the U.S.," said Wilson of the ICC.

Despite the escalating trade tensions, financial markets have remained relatively calm. "What's particularly interesting this week is the disconnect between the reaction of the financial markets (...) and the reaction of companies, who I think remain acutely concerned about the direction of tariffs, U.S. trade policy, the inherent risks of that," Wilson told Reuters.

This stands in contrast to the selloff seen in April, when an earlier wave of tariff announcements led to sharp declines in equities and U.S. Treasury prices. Trump initially paused implementation for 90 days but has now extended the deadline to August 1.

Investors appear to be pricing in a 10 percent baseline tariff. However, Trump suggested this week that the rate could climb as high as 20 percent for some countries.

Wilson said the administration is trying to "see how high they can get the number without freaking out the financial markets." He also noted that officials have touted tariffs as a significant source of revenue. Treasury Secretary Scott Bessent said the U.S. had collected about US$100 billion from tariffs so far this year, with a projection of $300 billion by year-end.