FIDEL CASTRO, always full of bluster, says Cuba will never change its socialist ways. He says he might cut off ties with America altogether by shutting down the U.S. Interests Section in Havana. He's threatening to flood America with a new wave of refugees. We've heard all this before. It's Castro boilerplate.

But there is something new. Cuba is now in deeper trouble, both economically and politically, than at any time in the 43 years of Castro's rule. Not only is Castro slipping mentally and physically, but he's lost most of his friends around the world. Venezuela, whose president is onetime Castro acolyte Hugo Chavez, has halted shipments of subsidized oil, forcing Cuba to institute blackouts. Despite Castro's grousing, the Russians dismantled their massive Cold War listening post in Cuba after having terminated their annual multi-billion dollar subsidy a decade ago. Since September 11, the flow of European tourists has slowed so drastically that 12,000 hotel rooms have been closed up. And the sugar crop, once Cuba's chief export, is approaching its lowest levels of production in more than a century.

With the pressure on, now is not the time to bail out Castro and his failed regime. Yet that's precisely what a growing group of business leaders, agricultural lobbyists, and members of Congress want the United States to do. They're clamoring to lift the trade embargo, the travel ban, and the requirement that Cuba use only cash, not credit, in buying U.S. medicine and food. The argument is that an opening to Cuba will lead to liberalization and maybe even democracy. It's a bad argument.

We know this from the way dictators act generically, and Castro specifically. Tyrants--Stalin, Hitler, Saddam, Arafat--regard concessions by their foes as acts of weakness to be exploited. But pressure, external and internal, is another matter. Dictators cannot ignore pressure. They must respond, and can thus end up being the ones who make concessions. When Castro has faced domestic economic pressure and America's steady refusal to open full economic relations--as in 1965, 1980, and the early 1990s--he's blinked. In 1965, he announced Cuban Americans could come pick up relatives at a Cuban beach. In 1980, he dispatched the Mariel boatlift. After Russian aid was withdrawn in the 1990s, Castro created a crisis by casting off hundreds of rafts with refugees eager to reach Florida 90 miles away.

But forced migration hasn't been Castro's only tack. Confronted by a deep economic downturn in the 1990s, Castro instituted free-market reforms. He legalized holding dollars. He allowed Cubans to open restaurants and hotels in their homes. He encouraged foreign firms to invest in joint ventures with Cubans. These reforms weren't sweeping, but the point is Castro didn't willingly adopt them. He was forced to, if only to relieve the pressure on his government. Pressure, not concessions, worked.

Castro is under far greater pressure now than in the 1990s. "In a country where unemployment and underemployment taken together exceed 50 percent, the average GDP per capita is a mere $1,500, less than every other western hemisphere nation except Haiti," notes Jerry Haar of the University of Miami. The experience of foreign investors, supposedly protected by Cuba's touted Foreign Investment Law No. 77, has been excruciating. They've been slapped with fraudulent back taxes and had their development plans stolen. The current economic slump has caused Cuba to default on debts to private banks and firms in France, Spain, Japan, Canada, Chile, and Venezuela. Last year, Cuba devalued its peso 18 percent. Nothing has worked.

The pressure has rattled Castro. Since President Bush announced his new Cuban policy of carrot and stick last May, Castro has been frantic, irrational, counterproductive. He insists the U.S. Interests Section is grossly violating Cuba's sovereignty by handing out free radios so listeners can tune into Radio Marti (or any other station). Castro maintains that free radios constitute a serious diplomatic breach. And rather than accept Bush's insistence on democratic and free-market reforms, Castro recently organized a petition drive in favor of socialism. Now he expects us to believe it was signed voluntarily by 99.2 percent of Cuban adults. The national assembly took up the matter and, after three days and 168 speeches, "irrevocably" declared socialism the way of life in Cuba. This, by the way, nullified the authentic Varela petition, gathered by democratic dissidents and endorsed by former President Jimmy Carter when he visited Cuba in May. It called for free elections and capitalist reforms.