Colombia seeks diplomatic and commercial relations with all countries, regardless of their ideologies or political or economic systems. For this reason, the Colombian economy is very open, relying on international trade and following the guidelines given by the international law. Regional relations remain good despite occasional issues with neighbors, especially regarding spillover from Colombia s armed conflict, including cross-border guerrilla crossings, the flow of refugees, and the spread of drug crops. These issues are of particular concern to the bordering countries of Brazil, Ecuador, Panama, Peru, and Venezuela. For example, Ecuador has closed its main border crossing with Colombia every night since August 2002, when evidence emerged that Colombian guerrillas and paramilitaries were asserting control over Ecuador s border communities. On May 1, 2004, Ecuador placed further stringent visa restrictions on Colombians seeking to enter Ecuador. Relations with Nicaragua and Venezuela have been strained over territorial disputes. Bilateral committees are negotiating the dispute with Venezuela over waters in the Gulf of Venezuela.