Since the early 1960s, the United States has maintained an embargo on Cuba through various laws, regulations, and presidential proclamations regarding trade, travel, and financial transactions. A stated purpose of the embargo--the most comprehensive set of U.S. economic sanctions on any country--is to deny hard currency to the Cuban government. The embargo, which the President has broad authority to modify, is implemented primarily by the Department of the Treasury (Treasury) through regulation of financial transactions with Cuba and by the Department of Commerce (Commerce) through regulation of the export of commodities, software, and technology to Cuba. Modifications to the embargo by legislation and presidential policy directives in the 1990s and early 2000s alternately eased and tightened restrictions on travel, remittances, gifts, and exports to Cuba. In September 2009, responding to legislation passed in March and presidential policy directives issued in April, Treasury and Commerce published regulatory changes that further ease some embargo restrictions.