Three months ago, things were looking pretty good for Tim Fulton and Ramper Innovations, a manufacturer of airplane equipment based in Sitka, Alaska.

Mr. Fulton was spending his days inside his workshop doing what he loved: building the company’s main product — a fold-up conveyor belt that unfurls in the belly of a plane to load and unload cargo or luggage. He had an order from the U.S. Air Force that he was confident would serve as a catalyst and bring in new customers from Asia and the Middle East while luring potential investors.

Then, the tariffs from President Trump struck.

The New York Times heard from Mr. Fulton and hundreds of other American business owners who said they have been stunned into paralysis by Mr. Trump’s barrage of tariffs. They are reassessing their product lines and supply chains and even putting their operations on hold.

Mr. Fulton, 66, was floored at the size of the tariffs and how quickly and chaotically they were applied. There were tariffs on Mexico and Canada and steel and aluminum. Mr. Trump hit dozens of countries with higher “reciprocal” tariffs he then put on hold when financial markets crashed. China struck back and the import tariff on Chinese goods ratcheted up to 145 percent.

Even though Ramper makes its products in the United States and buys as much of its components as possible from American companies, there is no getting around the tariffs. Some essential parts, such as motorized and static rollers from Japan, are only available overseas. The raw materials needed to build other critical parts are also imported. Most of Ramper’s U.S. suppliers rely on imports for some part of their supply chain.

Ramper raised its price 17 percent — a ballpark estimate for how much the tariffs would inflate its costs. Mr. Fulton also warned prospective customers that he may need to increase his price further if tariffs pushedhis costs up by more than 5 percent. Prospective customers balked at the higher prices and the uncertainty of what the final price might be.