U.S. President Donald Trump last week announced that the United States would impose tariffs on steel and aluminum imports. The news was greeted with dismay by U.S. trading partners and experts, with many warning of retaliation and disastrous consequences for the global economy. Trump responded by tweeting that "trade wars are good and easy to win." He is wrong on both counts. There are no good trade wars and there are no winners.

A mix of factors produced Trump's decision to announce a 25 percent tariff on steel imports and 10 percent on aluminum imports. First, there is his belief that the U.S. has been taken advantage of by its trading partners; proof for him is its shrinking manufacturing workforce and its persistent trade deficits. The call for nationalist and protectionist trade policies is perhaps the only constant in Trump's political statements.

Experts insist that his reasoning and logic are wrong — he ignores trade in services, manufacturing jobs have been lost for a variety of reasons, and a trade deficit is not a revealing indicator of economic health — yet other factors behind his announcement are more worrisome.