From Kennedy to Obama, 50 years of secret talks

Beyond the public animosity, stark statements and a trade embargo, there is another side to US-Cuba relations: exploratory missions, discreet negotiations and hands extended - in hotel hallways, airport waiting rooms and even the Vatican.

Barack Obama, who arrives in Havana on Sunday (local time) for the first visit by a sitting US president in nearly 90 years, will be the one remembered for opening a new chapter in ties between the United States and Cuba.

But he is not the first to have tried. For more than half a century, others have taken a stab at it, with the same buzzword always in mind: discretion.