WASHINGTON — At the rockiest annual meeting of major Western powers in decades, President Trump criticized the tariffs imposed on American goods as “ridiculous and unacceptable” and vowed to put an end to being “like a piggy bank that everybody is robbing.”

Behind Mr. Trump’s outrage is his belief that the United States is at a disadvantage when it comes to global trade and is on the losing end of tariffs imposed by other nations. But to many of the country’s trading partners, the president’s criticisms ring hollow given that the United States places its own tariffs on everything from trucks and peanuts to sugar and stilettos.

“While the system has problems, it is in no way ‘unfair,’ to the U.S., which as a hegemon has set the rules and the exceptions to the rules,” said Susan Aaronson, a professor at George Washington University’s Elliott School of International Affairs.

The United States has long been the biggest champion of global trade, viewing the opening of borders as essential to strengthening not only its economy but the global economy as well. It led the way in building the international trading order in the 20th century, rising to become the world’s predominant economy. Tariffs were used as a way to offer protection for certain industries, but free trade was considered the tide that would lift all boats because all countries involved would benefit.