If a nation faces some future peril due to some degree of overpopulation, while the world as a whole faces greater future peril due to a markedly larger degree

If a nation faces some future peril due to some degree of overpopulation, while the world as a whole faces greater future peril due to a markedly larger degree of overpopulation, then the people of that nation are likely better off not opening their borders. I have yet to decide whether the present situation of the USA fits this description, but it is at least not far fetched.