The precariousness of that relationship has added urgency to the debate over how fast the Cuban government needs to implement the reforms Raúl Castro endorsed. Old-guard leaders warn that a liberalized market economy could turn Cuba into a less egalitarian society and provide an opening for the United States to destabilize the government through a flood of private investment. Reformists, including some of the country’s leading economists, say the current state of the economy is untenable.

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The reality is that the island’s social welfare achievements cannot be sustained if current economic and demographic trends hold. Cuba is currently ranked in the top tier of the United Nations Human Development Index, a measure of a country’s education level, life expectancy and other variables. That’s an achievement matched by only two other countries in Latin America and the Caribbean, Argentina and Chile.

Wages in Cuba are worth roughly 28 percent of what they were before the collapse of the Soviet Union, according to the Center for the Study of the Cuban Economy at the state-run University of Havana. The devaluation has turned workplace theft into a major problem. It has also led tens of thousands of Cuban professionals to emigrate to the United States and elsewhere in Latin America in recent years in search of a better life. The country’s birthrate is declining, while its elderly are living longer.

The agricultural sector remains stymied by outdated technology and byzantine policies. A foreign investment law Cuba’s National Assembly approved in March has yet to deliver a single deal. Adding to the challenges, the Cuban government has pledged to do away soon with its dual-currency system (which includes a dollar-pegged peso established in the 1990s when tourism opened up), a process that could drive up inflation. Yet against the picture of stagnation is the growth of a new class of private-sector employees, now nearly 500,000 strong. That’s not a huge number in a nation of 11 million, but they are a marvel of ingenuity in a place where running a private restaurant requires buying virtually all ingredients on the black market. Basic staples, like potatoes, must be purchased as contraband in Cuba.

Many of those building small businesses, such as bed-and-breakfasts, are Cubans who returned with savings earned abroad and those with relatives outside the country who provided start-up capital. All struggle with the bureaucracy, since they are unable to import legally items as basic as mattresses and pillows. Bringing items from the United States is onerous and complicated by American sanctions. Cuban authorities appear conflicted about the growing private sector. While they welcome the employment and tax revenue it generates, bureaucrats are throttling businesses that are doing particularly well and forcing some to become joint ventures with the state. The underlying message seems to be: We want prosperity but not overly prosperous individuals.

Washington could empower the reformist camp by making it easier for Cuban entrepreneurs to get external financing and business training. That type of engagement is unlikely to succeed unless the United States abandons its policy of regime change. Cuba’s economic transformation may be proceeding slowly, but it could well lead to a more open society. For now, continued antagonism from Washington is only helping the old guard.