However, if that capital is comming from abroad, then this is not a particular cost that nation has to worry about. I know there are other arguments.
Let’s assume that North Korea is really good at producing coffee brewers and South Korea is not. For the sake of the argument, we assume that trade occurs between those two countries only. South Korea’s capital and labor forces will therefore not waste time, money and opportunity costs for building up an industry that may not be able to compete even in the long run, but instead buy the brewers from NK and use them in, say, coffee shops.
Suddenly, SK’s government decides to levy import tariffs on NKean brewers. In order to satisfy an existing demand for new brewers, capital and labor have to be employed to produce brewers. It may very well be that many of those who had previously been working in coffee shops will now find employment in brewer factories. The overall amount of coffee shops will decrease which means that a previously profitable market niche was destroyed by an artificially created need for coffee brewer production factories. In other words, Joe Sixpack will not have a coffee shop to go anymore.
I don’t see how that furthers the national welfare at all.