For anybody who thought the midterm elections made Barack Obama irrelevant, the explosive news about U.S.-Cuba relations should serve as a wake up call. American presidents have broad foreign policy authority and President Obama will be able to make headlines until the moment his successor is sworn in.

It will take a few days for the whole story to become known, but there is no doubt that this is big. The U.S. and Cuba are going to restore diplomatic relations after a half-century of estrangement, the U.S. Interests Section in Havana is going to become an embassy and, if the Senate concurs, an American diplomat will take up residence as our ambassador on the island.

This is one of those cases, increasingly rare, where President Obama can please his base while serving the national interest. The standoff with Cuba serves no real American interest and hands our enemies a useful propaganda tool. Furthermore, a policy that denies Americans the right to travel to countries of their choice is an infringement of personal liberty that could only be justified by a serious security concern. (A travel ban to Syria, for example, might have some merit.) The argument that Cuba, however bad its intentions, poses such a concern has been a joke since the fall of the Soviet Union, and there is no sound justification for limiting the rights of Americans to visit the island.

That said, U.S.-Cuba relations have long been and will likely remain one of those prickly and complicated subjects that many people pontificate about but very few understand. To begin with, the freeze in relations and the embargo have a more complicated place in the political strategy of the Castro regime than is widely assumed. U.S. presidents going back to Richard Nixon have tried through backchannels to move toward a new relationship with Cuba, and the Cubans have more than once pulled back from negotiations that could have ended the estrangement decades ago.

So why have the Cubans given Obama a prize that they withheld from presidents like Carter and Clinton? It’s all about context. The Castro brothers are getting older, and the outlines of a post-Castro power structure are emerging. The oil crash and the mounting problems of Venezuela’s embattled government make the Cubans nervous; Venezuela replaced the USSR as Cuba’s sugar daddy, supplying heavily discounted oil to help keep Castroism alive. At the same time, the Obama administration is probably the most sympathetic U.S. administration Cuba is likely to get, so it’s a good time to explore the possibilities of an improved relationship.

But there’s another thing to keep in mind. The Cubans are very close observers of the American scene. They understand—nobody better—that many of the provisions of the embargo have been enacted into law by Congress, and despite an evolving consensus on the right that the Cuban embargo has passed its sell-by date, the new Congress is unlikely to go very far very fast in dismantling the complicated legal limits on economic relations.

That’s a good thing from a Cuban point of view, not a bad one. The Castro government isn’t dying to have hundreds of thousands of well-heeled Cuban-Americans descending on Havana and buying the island back as foreign investors. Fidel and Raul have never wanted a total end to the embargo; they have understood for decades that the embargo acts to protect their socialist experiment. If the U.S. repealed the embargo, the Cuban government would have to choose between two unattractive courses. It could move toward normal and open economic relations with the United States, swamping its underdeveloped and scrawny local economy with gringo dollars and influence (with Miami Cubans leading the charge), or it would have to enact a tight set of regulations aimed at keeping American and Cuban American money and investors from overwhelming the island. That would make it crystal clear to every Cuban citizen that the Cuban government needs to keep the island isolated and poor in order to protect its grip on power.

Cuba’s strategic objective has always been to keep the embargo up and to make the embargo look like America’s fault. This has always made for odd relations between Cuban authorities and do-gooding American liberals anxious to heal the breach and help a poor, third-world country. U.S. liberal agendas and Cuban agendas mesh much less than liberals often think, and the Cubans have at times deliberately sabotaged efforts by American liberals to improve relations.

In the case of Obama, the Cubans could have had a better relationship almost from day one—and one of the reasons poor Alan Gross has been held in prison for so long has been the unwillingness of the Cubans to remove the biggest obstacle to an improved relationship with an Obama administration that, from their point of view, may have been too eager to end the embargo. If Obama had the power to drop the embargo tomorrow, it’s likely that Mr. Gross would still be in jail.

But the midterm elections give Cuba an insurance policy. Since Havana has a sense that Congress will slow things down and limit the changes Obama can actually make to the relationship, it appears to be ready to take a few more steps down the road to a normal diplomatic relationship. Meanwhile, the changes that Obama can make within the confines of the Helms-Burton law that keeps control of the embargo in Congress are ones that Havana, worried about declining support from snake-bit Venezuela, finds attractive. More yanqui tourist dollars and a carefully hedged and limited uptick in trade will help stave off the worst and buy time for a government that, one suspects, isn’t sure what to do next.

Bringing an end to the embargo and to the absurd travel ban limiting the rights of U.S. citizens to visit a neighboring country is good policy, if nothing else, but nobody should expect U.S.-Cuban relations to go into honeymoon mode anytime soon. For Cuban nationalists—not just communists—Cuba is vulnerable to being overwhelmed and pulled apart by the U.S. Cuban Americans wanting to buy the island back, an influx of American investors and tourists, economic incorporation into the dynamic Florida regional economy—all this would raise living standards in Cuba, but it would also challenge Cuba’s identity in ways that nationalists find very worrying.

From a U.S. point of view, the transition to a post-Castro Cuba is something very much to be desired on human rights grounds (since the end of the Cold War there has been no serious security threat from the island), but the transition is likely to be difficult. The end of communism—which Cuba’s government is by no means ready to contemplate—will likely come no matter what Havana does, and it is likely to be as disruptive and painful in Cuba as it was in most of the old Soviet zone. At the very least, this could create a serious immigration crisis if the economy is in trouble and the central government is weak. For the last thirty years, America’s attitude toward Castro has paradoxically echoed its attitude toward earlier Latin caudillos operating unsavory regimes: we tolerated unloveable strong men because we valued stability.

A gradual approach to the Cuban transition is in America’s interest. We do not want an economic and social collapse in a neighboring state. We do not want to see frantic Cubans struggling to escape an imploding economy as the government lost the ability to prevent waves of migrants setting out for our shores. We also do not want civil war in Cuba. Peaceful evolution in a context of growing relations and trade is the best scenario Americans can hope for. This new agreement on balance makes that more likely, and is therefore to be celebrated whatever one’s views of the Castro regime.

There will be costs, especially to other Caribbean economies. If Cuba really does open up to U.S. tourism, expect other Caribbean destinations to suffer. The Caribbean tourist industry has been built on the assumption that Cuba is closed to American tourism. Jamaica and other countries could face real problems if a re-opened Cuba changes the dynamics—as it almost certainly will.

Cuba has been ruled by the Castro brothers for more than half of its existence as an independent country. Ultimately the test of dictators is what they leave behind. Men like Chiang Kaishek, Lee Kwan Yew, Agustin Pinochet and Francisco Franco, whatever their crimes and shortcomings—and these should never be minimized or dismissed—left their countries better positioned for the future. Rulers like Papa Doc, Benito Mussolini and Vladimir Lenin wrecked their countries while holding power. While their execrable failures as economic leaders and planners will keep the Castros out of the front ranks of the modernizing tyrants, the future will tell us to which class of dictator the Castro brothers belong. In the meantime moving toward a normalized relationship with the island is in the interest of the United States and the Cuban people.