Setting aside the debatable morality of nationalism, protectionism just doesn't work well in the long term. A good place to start: https://en.wikipedia.org/wiki/Protectionism
> There is a consensus among economists that protectionism has a negative effect on economic growth and economic welfare, while free trade, deregulation, and the reduction of trade barriers has a positive effect on economic growth. In fact protectionism has been implicated by some scholars as the cause of some economic crises, in particular the Great Depression.
> There is a consensus among economists that protectionism has a negative effect on economic growth and economic welfare, while free trade, deregulation, and the reduction of trade barriers has a positive effect on economic growth. In fact protectionism has been implicated by some scholars as the cause of some economic crises, in particular the Great Depression.