The U.S.-Mexico border is considered a pivotal crossroads in the Americas. Other geopolitical border tensions have simmered in the Americas, including those between Haiti and the Dominican Republic, Nicaragua and Costa Rica, Colombia and Venezuela, and increasingly Mexico and Guatemala, as Central American migration to the United States has increased in response to drug-related violence in Honduras and El Salvador (→ Transnational Migration, I/44). The U.S. occupation of Guantanamo on the island of Cuba has also been a source of tension in the Caribbean.