When in a bind, Cuba's Castro brothers sometimes ease their repressive grip on the island's population. Case in point: during the current economic crunch, President Raúl Castro has released some two dozen political prisoners, revived a lapsed self-employment experiment, and allowed foreigners to lease land for 99 years. Impressive, except we've seen this movie before.

And to remove any doubt about its meaning, President Raúl Castro reportedly told his National Assembly that it does not signal a change in the 50-year-old anti-American police state. Which is why the United States should not significantly alter its equally long-lived trade embargo. The tougher it gets for the regime, the more likely that a few small freedoms will last longer -- hopefully until the two brothers go to the great commune in the sky.

It may be useful to remember that the harshest periods of the brothers' rule were when their coffers were flush and the revolution was strong. That's when the Soviet Union supported it with subsidies worth up to $6 billion a year as a regional arms trafficking and subversion hub. During that time, the regime reportedly held as many as 60,000 political prisoners, according to some estimates.

Yet in 1980, when outside help wasn't enough to pay the bills and thousands of Cubans took to the streets, then-president Fidel Castro allowed nearly 125,000 citizens -- some from prisons and mental hospitals -- a one-time good deal to flee to the United States. It was either appear magnanimous or lose control.

After subsidies dried up with the Soviet collapse in 1991, he licensed some 200,000 workers to earn their livings as cuentapropistas, self-employed street vendors and taxi drivers. At the end of the decade, when the economy had adjusted and Venezuela started providing subsidized oil, many permits were not renewed.

During the same period, the Cuban government began inviting foreign businesses to engage in joint ventures with state enterprises. In 1999, a project with a Canadian firm to refurbish a Soviet-built power plant seemed on track until the regime arbitrarily terminated the partnership and used the company's proprietary plans to shop for new partners, sinking a $9 million investment.

Now facing a cash crunch on the heels of a disastrous sugar harvest, brother Raúl is consulting Fidel's old playbook -- releasing jailed dissidents, ramping up self-employment, and making nice to foreign businesses, which, by the way, must abide by Cuban policies of denying workers' rights, in violation of International Labor Organization conventions. Meaningful reform? You be the judge.

Last year, President Obama rolled back Bush-era restrictions on family-member travel and remittance payments, and promised to allow U.S. companies to provide cell phone and satellite telecommunications services. Now he is about to encourage visits by academics and artists in a return to Clinton-era policies of purposeful engagement. Such measures might foster more people-to-people contact, but he should be careful about going much further.

The more radical 2010 Travel Restriction Reform and Export Enhancement Act (H.R. 4645), reported out of the House Agriculture Committee on June 30, would streamline financial transactions with Cuban banks to speed U.S. farm exports and lift the U.S. ban on tourist travel to the island. While enhancing sales is a good thing, a horde of American vacationers now could revive the army-run tourist industry and kill the current cuentapropista revival.

Tempting as it may be to view Cuba's tactical retreats as reforms, they are stopgaps. However, for as long they last, they provide certain benefits to ordinary Cubans. In that sense, the Obama administration and Congress would do well to stay the current course and abide by principled policies designed to pry open access to individual freedoms for Cubans wherever possible. To tweak U.S.-Cuba policy and perhaps minimize the embargo's impact on American businesses, U.S. policymakers could:

• Link seeming concessions to more positive behavior. As U.S. officials urge Raúl to release all prisoners of conscience, they could caution against booting them out of their own country.
• Take advantage of resurging self-employment. Business information and news of micro-financing opportunities on U.S. official broadcasting to the island might fuel popular expectations of further liberalization.
• Facilitate free expression by easing more U.S. restrictions on cell phone and equipment sales, and service agreements consistent with broader U.S. technology transfer limits. Wider ownership of laptops, mobile phones, and other consumer electronics (now legal in Cuba) can further complicate the regime's ability to control communication.
• Consolidate America's position as a key goods supplier to the island. President Obama could urge Congress to expand the list of what can be exported under the embargo's cash and carry sales rules that now contemplate food, clothing, and medicine.

To sustain leverage over Cuba's government on the cusp of transition, the United States should continue to:

• Deny financial support and credit until Cuba releases its captive labor force and pays creditors, and
• Condition normal diplomatic and economic relations on respect for human rights and civil liberties such as freedom of expression, of assembly, movement, and access to due process of law.

Since they came to power in 1959, the Castro brothers' goal has been the survival of their socialist dream. Adaptability has been the key to success, retreating at critical junctures without altering the regime's basic structure. Such measures often looked like signs of change because we wanted to see them as such. On close inspection, they were skillful maneuvers to get through a crisis.

A number of congressmen and business groups are now saying that Raúl is sending friendly signals to Washington like crazy. Perhaps. But it would be crazy for us to believe he would admit that a life spent building a repressive police state was just a mistake. Rather, we would be better off dealing with new leaders willing to take Raúl's retreats to the next level by guaranteeing human rights and civil liberties, respecting ordinary citizens' right to choose their leaders, and allowing a market economy to flourish.