It is in the US: "Throughout our nation's history, foreign-born men and women have come to the United States, taken the Oath of Allegiance to become naturalized citizens, and contributed greatly to their new communities and country. The Oath of Allegiance has led to American citizenship for more than 220 years."
Now I haven't looked into many other countries, but at least in the EU I know that there's many proxies for loyalty when applying for citizenship. And many countries do not accept dual citizenship, which should make things clear for you hopefully.
