United States allows people to have dual citizenship and it does not oppose dual citizenship. However, the country will allow US citizens to have dual citizenship only in certain circumstances. A US citizen may become a citizen of a foreign country by birth or by getting married to a foreign national. But US citizens must remember that they must not willfully apply for citizenship and become citizens of foreign countries and in this case, they are likely to lose US citizenship. US citizens may become citizens of foreign countries by the automatic operation of law and US citizens may not get into trouble if they automatically become citizens of foreign countries, by birth. This also applies to US citizens who get married to foreign nationals and they may become citizens of foreign countries based on marriage.
Likewise, naturalized US citizens will not lose their previous citizenship. Moreover, US laws do not require such naturalized US citizens to choose one citizenship or the other and they may keep their original citizenship. But they may have to give up their original citizenship, if their countries of birth do not allow dual citizenship. Hence, US Green Card holders must first check with their home countries, before applying for US citizenship as the citizenship laws of all the countries are not the same and there are few countries that oppose dual citizenship. US citizens who are granted another citizenship may not lose US citizenship but people who wish to become citizens of foreign countries and relinquish US citizenship, may lose US citizenship.
People who wish to forfeit US citizenship, can apply for foreign citizenship and give up US citizenship. Though the United States does not oppose dual citizenship, due to various reasons, the country does not encourage it. That is because, people who have dual citizenship must follow and respect the laws of both the countries. However, citizens of foreign countries will have to consider few other factors before applying for US citizenship. If they belong to countries that do not recognize dual citizenship, they may be required to choose one citizenship or the other. Dual nationals must obtain US passports and passports from the other foreign country and that is because, they must use their US passports to travel to the United States and passports of the other foreign country, to travel to that foreign country.
Similarly, United States has the right to impose its laws on the dual nationals while they travel to America and similarly the other foreign country also has the right to enforce its laws while the dual nationals travel to that foreign country. At times, dual citizenship is likely to prevent the United States from providing protection when the dual national is abroad and due to such reasons many foreign countries do not recognize dual citizenship. Similarly, dual nationals may be required to give up US citizenship in certain circumstances and if dual nationals are employed by the government of America, they may be required to up their previous citizenship. Likewise, if they are employed by the government of the other foreign country, they may be required to forfeit US citizenship.