Fidel Castro spearheaded a revolution that was successful in removing President Fulgencio Batista from power in 1958. Relations between Washington and Havana deteriorated rapidly soon thereafter, and within a few years the United States broke diplomatic relations (January 1961), was influential in having Cuba thrown out of the Organization of American States (January 1962), and imposed a total trade embargo on Cuba (February 1962). Tensions between the United States and Cuba peaked during the so-called "Cuban Missile Crisis" of October 1962, but have since settled at a lower, albeit still high, level. Low level diplomatic relations were resumed in 1977 when the United States and Cuba opened “interest sections” in Havana and New York, respectively.

As a counterweight to U.S. power, the Cuban government entered into a series of agreements with the Soviet Union that led the two countries to establish close economic and political ties, including military and defense arrangements. Relations between Cuba and Russia became strained after the dissolution of the Soviet Union, which led to the cessation of all assistance from that country and, subsequently, Russia.

Under Castro, Cuba became a highly militarized society. Massive Soviet military assistance enabled Cuba to upgrade and increase its military capabilities, which in turn were used to send military units abroad. As of August 2008, there is much uncertainty about Cuba’s future course. This uncertainty began in August 2006, when Fidel Castro, battling illness, ceded power to his brother Raul Castro. However, the change of power was made permanent in February 2008 when Castro announced that he would not accept another term as president, which led to Cuba’s Parliament electing Raul Castro as the new president on 24 February 2008. It is unclear how much influence Fidel Castro continues to have over policy making in Cuba and thus how much real power Raul Castro possesses. An attempt may be underway to form an alliance between Cuba, Venezuela, and Russia to counterweigh U.S. influence in Latin America.

Nuclear

Cuba does not possess nuclear weapons, and there are no credible reports of Cuban efforts to acquire these weapons. In 2002, Havana acceded to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), ratified the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (Treaty of Tlatelolco), and deposited an Additional Protocol with the IAEA.

In the 1980s, Cuba raised international safety and proliferation concerns with the construction of a nuclear power plant in the south central province of Cienfuegos, near Juragua, about 180 miles south of Key West, Florida. The project started in 1976 when the Soviet Union and Cuba signed a formal agreement to build two 440-megawatt pressurized water reactors to provide electricity for Cuba's growing energy needs. Construction started only in 1983 and was suspended in 1992 due to the termination of Soviet financial aid to Cuba after the collapse of the USSR. Since 1995, attempts by Cuba and Russia to obtain international financing to finish the project revived U.S. concerns about its safety and proliferation effects.[1] Cuba had not signed the NPT or the Tlatelolco Treaty at that time and there were allegations by Cuban nuclear power officials about existing problems that could affect the safe operation of the reactors.[2] Cuba and Russia failed to find international support for the project and on 17 January 1997, then Cuban President Fidel Castro announced its "indefinite postponement". Russia retained interest in completing the nuclear plant until December 2000 when President Vladimir V. Putin visited Cuba and was told by President Castro that Cuba was no longer interested in completing the twin 440-megawatt reactor plant.[3]

Biological

While both public and private persons have with some frequency alleged that Cuba has supported a secret biological warfare (BW) program, no convincing proof of the existence of such a program has been presented. Cuba signed the Biological and Toxin Convention (BWC) in 1972 and ratified it in 1976.

Since approximately 1981, Castro has been instrumental in Cuba's acquiring a powerful biotechnology capability which is possibly the most advanced among developing countries. Certainly, Cuba’s biotechnological and medical industries are the largest and most sophisticated in Latin America as demonstrated by its large-scale production of pharmaceuticals and vaccines. This capability is being used to develop and produce products for exports and the income from these exports might be larger than all other income-generating endeavors with the exception of sugar and tourism.

Chemical

Cuba has never been known to possess chemical weapons; it signed the Chemical Weapons Convention in 1993 and ratified it in 1997.

Missile

Cuba is not suspected of having acquired or produced long-range ballistic missiles.

In October 1962, Cuba was the stage for the most dangerous confrontation between the United States and the Soviet Union during the Cold War. In May 1962, Soviet Premier Nikita S. Khrushchev secretly began deploying medium range ballistic missiles (MRBM) and intermediate range ballistic missiles (IRBM) to Cuba as a means to counter the U.S. lead in strategic missiles and protect Cuba from an U.S.-sponsored invasion. Presented with photographic evidence of missile installations under construction, President John Kennedy chose naval blockade as the course of action against Soviet ships. The strategy proved to be successful and on 28 October, Khrushchev announced that he would dismantle the installations, expressing his trust that the United States would not invade Cuba.[4]

Sources:
[1] Scott Parrish, "Russia, Cuba, and the Juragua Nuclear Plant," NTI, May 1997, www.nti.org.
[2] "Nuclear Safety: Concerns with the Nuclear Power Reactors in Cuba," GAO/RCED-92-262, 24 September 1992, http://archive.gao.gov.
[3] Patrick E. Tyler, "Cuba and Russia Abandon Nuclear Plant, an Unfinished Vestige of the Soviet Era," New York Times, 18 December 2000, www.lexisnexis.com.
[4] "Cold War: Cuban Missile Crisis," Revelations from Russian Archives, Library of Congress, www.loc.gov; Laurence Chang and Peter Kornbluh, "The Cuban Missile Crisis, 1962," The National Security Archive, George Washington University, www.gwu.edu and "Cordon of Steel The U.S. Navy and the Cuban Missile Crisis," Department of the Navy, Naval Historic Center, www.history.navy.mil.