Fidel Castro again bristled at the Obama administration's steps toward improving relations with Cuba, writing in a May Day message that the U.S. would like to see Cubans "return to the fold of slaves."
The former president's column was published in official newspapers as Cuba celebrated international worker's day with a traditional march by hundreds of thousands of people across the sprawling Plaza of the Revolution.
Castro said he found "some new elements" in the Obama administration, which has eased restriction on travel and money transfers by Americans with family in Cuba.
"We are carefully studying and observing each of its steps," he wrote.
But Castro complained that Washington "is ready to forgive us if we resign ourselves to returning to the fold of slaves who, after tasting liberty, again accept the whip and the yoke."
"The adversary should not have any illusion that Cuba will give up," he wrote.
Those were the kind of words Castro once would have shouted during an hours-long speech before the start of the May Day procession. But illness has kept him from public view since July 2006 and officials ensured this year's parade moved along in a businesslike style, ending it after barely two hours.
Raul Castro, who succeeded the ailing, 82-year-old Fidel as president last year, presided over the march in a straw hat and white Guayabera dress shirt instead of his usual army fatigues. He chanted along with the crowd and grinned and waved from a high seating area, but did not give a speech.
Many Cubans sang and danced - others sweated and simply trudged along - as they followed the carefully controlled parade route through the concrete square where Raul Castro has his office.
They waved Cuban flags, pictures of the Castro brothers and of revolutionary icon Ernesto "Che" Guevara, and they hoisted cardboard signs promoting socialism and decrying Washington's 47-year-old trade embargo against the island.
Most of the placards thrust skyward repeated decades-old slogans like "Long Live Free Cuba," and "Socialism or Death," but some blamed "neo-liberalism" and free-market policies for the global economic crisis and recession.
Salvador Valdes Mesa, secretary-general of the Cuban Workers Confederation, urged Cubans to be more productive and efficient despite state salaries worth only about $20 per month.
In addition to allowing unlimited travel and money transfers for Cuban-Americans, the Obama White House has reduced restrictions on telecommunications between the U.S. and Cuba.
But top U.S. officials say they would like to see some Cuban political and social reforms before exploring normalizing diplomatic relations. Fidel Castro insists that Cuba should make no concessions in return for better U.S. ties.