The U.S. Steel Corporation plant on March 2 in Clairton, Pa. (Spencer Platt/Getty Images)

Regarding the March 2 front-page article “Trump draws his line on trade”:

Many people are disturbed by President Trump’s tweets. But perhaps more disturbing may be the inability of anyone in the White House to do simple arithmetic. There are roughly 85,000 people employed in iron and steel mills and ferroalloy manufacturing. There are nearly 1 million workers employed in the manufacture of automobiles , and if you add construction, rail and aerospace, the number of workers who need steel for their jobs grows enormously. Simple economics would suggest that if you raise the cost of an item, the price will go up and less will be purchased. The last time steel tariffs were instituted, the country lost 200,000 jobs. This tariff action was not well- ­conceived. Clearly, our president needs better advisers.

Gary Simon, Potomac

Unlike my current faculty friends who do not comment on President Trump, I am retired from the Wharton School after teaching finance for 42 years. Although neither Mr. Trump nor Donald Trump Jr. were my students, the former’s views on steel tariffs and protectionism are essentially what the founder of our school, Joseph Wharton, professed. He was a staunch Republican, an owner of Bethlehem Steel and president of the American Iron and Steel Association.

When he contributed $100,000 to the University of Pennsylvania in 1881 to found a “School of Finance and Economy,” he requested that the new school’s faculty advocate economic protectionism. Although that is not the case with Wharton’s faculty, this was obviously the case for some of its students.

Kenneth H. Thomas, Miami

With President Trump’s decision to impose tariffs on imported steel and aluminum, he again shows little understanding of basic economic principles and of second- and third-order effects of policies, and an unwillingness to learn from history.

Tariffs are pro-producer and anti-consumer. In this case, the tariffs would likely help a few hundred steel and aluminum companies and their employees but also hurt tens of thousands of consumers of steel and aluminum, as well as millions of their employees. Add to these the tens of millions of ultimate consumers who will end up paying more for their purchases.

Mr. Trump continues to remain oblivious to the consequences of his actions and policies. Imposing tariffs on imports will most certainly invite retaliation from our trading partners and lead to trade wars that will hurt all nations. Several of our prominent industries from agriculture to transportation will likely face retaliatory tariffs from others.

President George W. Bush imposed tariffs of 8 percent to 30 percent on steel imports in March 2002. The tariffs raised steel prices for consumers of steel, such as automobile companies, making them less competitive in global markets. The European Union announced it would impose retaliatory tariffs on imports from the United States and took the case to the World Trade Organization. Japan, South Korea, China, Switzerland and Brazil filed similar cases with the WTO, which ruled against the United States, and the tariffs were withdrawn in December 2003.

Vinod K. Jain, Ashburn