By Robert Plummer
BBC News Online Americas analyst
The decision by Mexico and Peru to recall their ambassadors from Havana shows that even in Latin America, Fidel Castro is now increasingly friendless.
Still going strong at 77, the Cuban president shows no signs of softening his grip on power. Indeed, he seems determined to preserve his diehard brand of socialism at any cost, even if that means alienating his fellow Latin leaders.
President Castro is determined to preserve socialism in Cuba
There was a time when concern for Cuba's human rights record among its neighbours was tempered by a sneaking admiration for its defiance of the United States.
The US embargo against Havana was seen as a punitive action against a small island nation that dared to go its own way in Washington's backyard.
But hardline Cuban communism holds few attractions as a model these days in a continent where pragmatic President Lula of Brazil is still the most admired left-wing leader.
Lula has maintained cordial relations with the Cuban leader while keeping his policies at arm's length.
By contrast, the regional leader who has come closest to adopting Mr Castro's ideology, Venezuela's Hugo Chavez, faces a possible referendum on his presidency as he struggles to cope with a sharply polarised society and a battered economy.
And while the Cuban president still dons his green military fatigues to deliver his May Day tirades against Washington, his sober-suited Mexican counterpart Vicente Fox deals with the US as an economic partner in the North American Free Trade Agreement.
Small wonder, then, that the simmering tensions between Mexico and Cuba over their differing attitudes to the US have boiled over once again.
The last time, in April 2002, Mr Castro picked a public fight with Mr Fox, alleging he had been forced to leave a United Nations summit in Mexico early so that he would not run into President George W Bush.
When the Mexican president denied the allegation, Mr Castro delivered one of his trademark two-hour diatribes, complete with taped extracts from a private telephone conversation with Mr Fox that he said proved his point.
President Fox has had a previous diplomatic row with Mr Castro
Now he has returned to the fray, accusing Mexico and Peru of doing Washington's bidding when they voted at the UN last month to condemn Cuba's human rights record.
It is equally plausible that they did so out of frustration at the increasingly harsh treatment of dissidents in Cuba.
Two years ago, opposition activists presented a petition to Cuba's national assembly calling for greater civil liberties.
Mr Castro's immediate response to the petition, known as the Varela Project, was to have a constitutional amendment passed declaring that the socialist system in Cuba was untouchable.
Crackdown on dissent
Since then, Cuba has moved to muzzle dissidents, imprisoning 75 of them last year and a further 10 this year after one-day secret trials.
In other ways, too, Mr Castro has gone into reverse gear, blocking the country's tentative progress towards a more market-oriented economy and restricting internet use for Cubans.
As a result, countries that thought they could promote gradual change in Cuba by engaging in dialogue with it are no longer seeking to hide their disappointment.
That includes the European Union, denounced by Mr Castro as Washington's "Trojan horse" after it dared to criticise the Cuban authorities' crackdown on dissent.
It seems clear that there will be no radical change in Cuba as long as Mr Castro remains in power - but the more intense the country's isolation now, the more traumatic the effect is likely to be when his death eventually comes.