There is nothing more dangerous than a political figure who promotes some kind of value-neutral policy (or even worse -- a BAD policy) by claiming that "God wants us to do this."
You are correct but they,as well as many of their successors knew this very well regarding God’s promise to Israel:
Gen 12:3
I will bless those who bless you,
And I will curse him who curses you;
And in you all the families of the earth shall be blessed.