Robert Higgs has it right.
Nearly everyone recognizes that murder, robbery, burglary, assault, battery, extortion, and fraud are wrong, and a strong argument may be made that if a government is to exist, it should occupy itself in preventing these wrongs and punishing those who perpetrate them.
But if I am simply buying from or selling to someone outside the national borders, what possible grounds may be advanced in justice to warrant the use of state force against me for doing so? To say that people should be punished merely for trading freely, by means of taxes or prohibitions, and threatened with prison terms if they violate prohibitionist laws, is an outrageous moral proposal, wholly apart from its economic counterproductivity. The "protectionists" and the state acting on their behalf are the true criminals here, not those who peacefully buy from and sell to whatever trading partners they choose.
Yet certain politicians and millions of their supporters shamelessly and publicly proclaim their desire for such blatantly immoral and genuinely criminal action by the government. What next? Will these same "protectionists" support killing off their competitors or herding them into concentration camps?