When Cuban MiGs blasted two civilian planes out of the sky over the Straits of Florida on February 24 1996, they also destroyed any chance of improved relations between Cuba and the United States as long as Fidel Castro remains in power. In Washington, outrage over the shoot-down resurrected the Helms-Burton bill, the most punitive legislation on Cuba since the early 1960s. On 12 March, President Bill Clinton signed the bill into law as the Cuban Liberty and Democratic Solidarity Act of 1996. In addition to assorted sanctions aimed at foreigners doing business in Cuba, the most consequential provision incorporates the US economic embargo into law. Heretofore, the embargo was based on presidential executive orders; it could be tightened or loosened at the president's discretion as conditions warranted. Under Helms-Burton, no president can lift or even relax the embargo until Fidel Castro and the existing Cuban regime fall from power. At a time when Cuba's domestic social and economic system is changing at break-neck speed, Washington's 35-year-old policy of hostility has just been chiselled in stone.