Advice for Trump on post-Fidel Cuba.

• Author: Bruno, James
• Position: TEN MILES SQUARE - Fidel Castro

I was a U.S. diplomat in Cuba. Here's what the new administration needs to understand.

At his rallies, Fidel Castro was fond of bellowing, "Socialismo o muerte!"--Socialism or death! Death finally caught up with the dictator last November, and Cuban socialism's days are likely numbered as well. The Cuban people soon will enter the post-Castro period after President Raul Castro steps down in two years, as he has promised. What comes after that is anyone's guess. To be able to have any influence in this transition period, Washington will need to identify which Cubans are in the best position to steer events.

As the United States goes through its own transition, the Trump administration will have to decide whether to continue President Obama's normalization of relations with Cuba or to slam on the brakes, demanding that Havana cease oppression of political dissidents and pursue concrete steps toward democratization.

In our approach to Cuba, we first have to understand what makes official Cuba tick. The reality is that the Communist Party may indeed be history, but one major player is likely not only to stick around, but to keep calling the shots. That player is the Fuerzas Armadas Revolucionarias (FAR), Cuba's armed forces. The FAR play a role outsized to their numbers, now around 90,000, down from double that during the Cold War years.

The FAR are widely considered to be Cuba's best-managed and stablest government organization and are held in respect by Cubans generally. They run the economy and control politics. Since he succeeded his brother as president eight years ago, Raul, who had commanded the FAR since the revolution, has expanded their role. More than half of the Communist Party's Politburo members have a military background, while the Council of Ministers is likewise dominated by active-duty or retired FAR officers.

The Cuban military controls 60 percent of Cuba's economy and takes in 40 percent of foreign exchange revenue. The FAR's so-called "entrepreneur soldiers" manage a wide docket that includes sugar and cigar production, tourism, information technology, and aviation. One in five Cuban workers is employed by the FAR's holding company, GAESA, which is headed by Raul's son-in-law, Luis Alberto Rodriguez Lopez-Callejas, an army brigadier who speaks English with a proper upper-class British accent.

I got to know Cuban military officers as the State Department's representative at monthly military meetings on "The Line"--the border...