In the twentieth century, US immigration policy turned generally restrictionist. Foreign policy concerns, however, led the government to permit and even, for a time, to stimulate Mexican migration to the United States. The US government has at times used its immigration policy as an instrument to achieve certain foreign policy ends; at other times it has sacrificed foreign policy ends in response to domestic pressures to control immigration. Some crises emerged mainly in the non-immigration sphere of U.S.–Latin American relations, though they included an immigration component. Immigration was a tool in the ideological cold war with Cuba. The concept of immigration deterrence through policy consistency and professional autonomy was routinely tested, instead, in US relations with Central American countries, especially with Sandinista Nicaragua. The US-Haitian relationship in the 1980s has been similar in structure to hegemonic relationships that the United States has established with other clients.