Praise be to Allaah. In order to answer this question, we must explain two things.
1 – Whether settling in a kaafir country is permissible
2 – Establishing whether there is a need to take the nationality.
With regard to the first matter, settling in a kaafir country is not permissible unless the following conditions are met:
1- There should be a legitimate need for settling in their country, which cannot be met in the Muslim lands, such as trade, da’wah, officially representing a Muslim country, or seeking knowledge that is not available in a Muslim country either because it does not exist there, or what is available is not of good quality. Or there should be fear of death, prison or torture, not mere harassment, for oneself or for one’s family and children, or fear for one’s wealth.
2- Settling there should be regarded as temporary, not permanent. It is not permissible to have the intention of staying there permanently; rather one should have the idea that it is temporary, because settling there permanently means that one has migrated (made hijrah) from the land of Islam to the land of kufr. This clearly goes against the ruling of sharee’ah that it is obligatory to migrate from the land of kufr to the land of Islam. Having the intention of staying there temporarily means that when the need to stay in the kaafir country no longer applies, one will get up and leave.
3- The kaafir country in which one wants to settle should be one which is at peace with the Muslims, not one which is at war with them. Otherwise it is not permissible to settle there. A country is regarded as being at war with the Muslims if it is hostile towards the Muslims.
4- There should be religious freedom in the kaafir country, so that the Muslim will be able to practise his religion openly.
5- He should be able to learn the laws of Islam in that country; if it is difficult for him to do so then it is not permissible for him to settle there because that implies that he is turning away from learning the religion of Allaah.
6- He should think it most likely that he will be able to protect and maintain his religious commitment, and that of his family and children, otherwise it is not permissible for him to settle there, because preserving one’s religious commitment takes precedence over preserving one’s self, one’s wealth and one’s family. Whoever meets this condition – and how difficult it is to meet it – is permitted to settle in the land of the kuffaar, otherwise that is forbidden to him, because of the texts which clearly forbid settling there and enjoin migrating from such lands, as is well known, and because of the great danger which that poses to religion and morals, which no one can deny except one who is arrogant.
Secondly: there should be a legitimate need for taking the nationality, such as the benefits for which the Muslim has settled in the kaafir country being dependent upon his taking the nationality. Otherwise that is not permissible for him, because taking the nationality is an obvious manifestation of befriending the kuffaar, and because it involves speaking words which it is not permissible to believe in or adhere to, such as approving of kufr or man-made laws. Moreover, taking the nationality may lead to staying in the kaafir land permanently, which is not permissible, as stated above. Having established these two points, I hope that Allaah will forgive the Muslims who settle in kaafir lands for the great danger that they have exposed themselves to, because either he is forced to settle there and necessity makes permissible that which is ordinarily forbidden, or to serve an interest which outweighs the harms. And Allaah knows best.
