Warm and cool: Cuba’s ties with USSR under Castro

The death of Cuban socialist icon Fidel Castro at age 90 on Friday stirred memories of his island nation´s close but at times fraught relations with the Soviet Union.

Mikhail Gorbachev, the last leader of the USSR, on Saturday hailed Castro for having strengthened Cuba in the face of an American economic blockade, praising his former counterpart for having left a "deep mark in the history of mankind".

But Gorbachev, 85, shied from invoking the cooling of relations between Cuba and the Soviet Union, telling Interfax news agency he would not discuss that period "on this day of mourning".

The end of the Cuban revolution in 1959, which propelled Castro to power, saw Moscow gain an ally in the backyard of the United States, its Cold War foe.

Initially Soviet authorities were uncertain about how to deal with the new leader in Havana.

But the US blockade, which increased pressure on Castro to find external support, led Cuba to develop its burgeoning relations with the Soviet Union.

Castro appealed to Soviet leader Nikita Khrushchev for help. Moscow provided Havana with fuel in exchange for Cuban sugar.

The move saw Cuba progressively become totally dependent on the Soviet Union.

Havana´s relations with the Soviet Union deepened further after Castro´s forces defeated the CIA-backed Bay of Pigs invasion in 1961, which led him to declare Cuba a socialist state.

The Soviet Union´s support for the Cuban regime was far from selfless, serving as a part of its broader Cold War confrontations with the United States.

In response to American ballistic missile deployments in Italy and Turkey in 1962, Moscow struck back by deploying its own missile to Cuba -- just 144 kilometres from the southern tip of the US state of Florida.

After a tense standoff between the rival superpowers, the world pulled back from the abyss as Moscow agreed to keep the missiles off Cuban soil in exchange for a US promise not to invade Cuba.

Castro was angered for not having been consulted on the deal, straining relations with Moscow.

In subsequent years Havana moved closer to the Chinese Communist regime while continuing to foster ties with Moscow, with Castro making his first visit to the Soviet Union in 1963.

In the later years of the Soviet era, Moscow invested heavily in the Cuban economy and provided it with significant military assistance.

In the final years of the Soviet Union, Moscow was struggling to meet its financial commitments to Cuba.

After a cutoff of Soviet bloc aid in 1989 nearly collapsed the Cuban economy, Castro allowed more international tourism and modest economic reform.

Ties between Moscow and Havana suffered after the collapse of the USSR in 1991 as the massive flow of financial aid from Moscow dried up.

President Vladimir Putin´s decision to close a Soviet-era intelligence base south of Havana in 2001 also chilled relations. Ties picked up a few years later when Moscow began reasserting itself in Latin America.

The Kremlin has since been striving to revive its ties with Cuba as Russia increasingly squares off against Washington over Ukraine and Syria.

Putin visited Cuba in 2014, agreeing to write off 90 percent of Havana´s Soviet-era debt, a sum amounting to $32 billion.