Trump's trade war destroyed manufacturing jobs and hiked costs: Federal Reserve study
President Donald Trump speaks during campaign MAGA rally at Southern New Hampshire University Arena. (lev radin /

President Donald Trump's tariffs are hurting some of the companies he promised to protect.

The president levied tariffs on hundreds of billions of dollars worth of imports from Asia, Latin America and Europe, and China retaliated with tariffs of its own -- which all helped kill jobs and increase manufacturing costs, reported Business Insider.

The Federal Reserve released a study late last month that shows the costs of Trump's trade war outweighed the benefits and plunged the already weakened manufacturing sector into one of its worst years for job cuts in the past decade.

"For manufacturing employment, a small boost from the import protection effect of tariffs is more than offset by larger drags from the effects of rising input costs and retaliatory tariffs," wrote authors Aaron Flaaen and Justin Pierce. "For producer prices, the effect of tariffs is mediated solely through rising input costs."

The trade war and an ongoing transition to a gig-based economy each threatened manufacturing companies last year, and that sector has been stuck in a recession since August before sinking even lower in August, according to the Institute for Supply Management.

Trump promised in 2016 that he would revive manufacturing, and insisted his tariffs would give U.S. companies a boost, but the Federal Reserve study shows that's not what happened.

"While the longer-term effects of the tariffs may differ from those that we estimate here, the results indicate that the tariffs, thus far, have not led to increased activity in the US manufacturing sector," the report noted.