The decision by the US and Cuba to renew diplomatic relations marks the end of “hard Castro-ism” on the communist island and a victory for pragmatic diplomacy. Cuban President Raul Castro helped pave the way for his US counterpart Barack Obama to make the politically delicate gesture by toning down the Havana government’s anti-American rhetoric after taking over from his older brother Fidel Castro in 2006.

Wednesday’s announcement would likely have been impossible under Fidel, the father of the communist island’s 1959 revolution. Fidel had carved out an image as the eternal enemy of “American imperialism,” an animosity made deeply personal by a string of failed assassination plots by the US Central Intelligence Agency during the Cold War.

But Raul, 83, has taken baby steps towards economic reform as well as a change in rhetorical style since taking the reins from his 88-year-old brother when the latter had a health crisis eight years ago. Ironically, Raul was long seen as even more of a hardliner than Fidel when he served as his brother’s defence minister. However, he said after taking office that he was willing to negotiate with the US as equals.

The move to end the Cold War standoff likely means the Cuban president is ready to compromise. The deal to normalise relations is not something that emerged overnight. It’s a process that’s been maturing and must imply some concessions.

The release of three Cuban spies from US prisons and an American from a Cuban jail -the exchange that preceded the historic announcement – is only the most visible part of the deal.

There had been signs of an emerging thaw in US-Cuban relations in recent months. In October, American officials attended a regional meeting on fighting Ebola that was hosted in Cuba. Cuba has won plaudits - including from US Secretary of State John Kerry - for sending scores of doctors and nurses to fight the epidemic in West Africa.

In another key moment that was broadcast around the world, Obama and Castro shook hands at Nelson Mandela’s funeral in South Africa in December last year.

But the detente seems to have originated one month earlier, when Obama told a fundraising dinner in Miami - the bastion of anti-Castro sentiment among the Cuban-American community - that it was time to admit the US’ five-decade trade embargo on Cuba had failed.

In Cuba, another key change was Raul Castro’s willingness to allow Pope Francis to act as a liaison for talks. Raul has also made symbolically important reforms at home, lifting foreign travel restrictions, opening more private sector employment, and allowing Cubans to buy cell phones, computers, houses and cars.

Moreover, he no longer calls Cuban emigrants traitors or “worms.” He has continued to rail against the embargo and refused to consider ending one-party communist rule. But he has also brought a more pragmatic style to Cuban diplomacy, winning the support of other Latin American countries - reflected in the fact that 30 leaders attended a summit of regional group CELAC in Havana last January.

However, both sides will have to work to maintain the momentum. The road ahead won’t be easy, but getting it right will be key for ties between Cuba and the US.