Opposition to immigration is a political stance advocating for restrictions or bans on both legal and illegal entry into a country, with proposals ranging from policy reforms to complete border closure and even repatriation of existing immigrants. A key argument centers on national identity, where research shows that exclusionary ethnic or racial definitions of identity strongly correlate with anti-immigration attitudes—though a 2015 study on Indonesia demonstrates that inclusive national identity can actually promote inter-ethnic harmony. Opponents also invoke national sovereignty, citing the Council of Europe's acknowledgment of states' right to protect borders and combat human trafficking, while others warn that isolated immigrant communities (or "parallel societies") can undermine social cohesion and cultural unity, as noted by researcher Jennifer Neal. Additionally, the importation of foreign cultural practices that clash with native laws and values, alongside concerns about net negative fiscal impacts on public services like medical care, frequently fuel opposition. Ultimately, these arguments blend concerns over cultural preservation, economic costs, and security, making immigration one of the most polarizing political issues globally.