JOHN Fugelsang, the ­American actor and ­comedian, had a little ­Twitter joke at the expense of the Republicans last week.

One was imagined denouncing his president - "'I can't believe Obama would interact with Communist Cuba,' he tweeted angrily on his Chinese-made iPhone".

As a point about selective amnesia, it was well made. The United States has been trying to isolate the troublesome island nation for 54 years: it has attempted an invasion; it launched harebrained schemes to assassinate Fidel Castro. US presidents have come and gone, but American attitudes towards the red menace 90 miles from Key West, Florida, have been unrelenting.

Meanwhile, US relations with the People's Republic of China have been "normalising" ever since Richard Nixon shook the hand of Mao Zedong in 1972. This is not because Cuba is more totalitarian than the Beijing regime and it is not because Castro's human rights record, lamentable as it has been, was ever remotely comparable to the ruthlessness inflicted on the people in the people's name by China's Communist Party.

You could call it realpolitik: Cuba could be harried; China could not. The fact that the Chinese hold title to a mountain of America's debts might also enter the equation. They possess vast economic power and supply many of the world's consumer goods. So is China's regime cruel, ruthless, "communist", godless? You bet. And are there other regimes with grisly records - Saudi Arabia, say - which enjoy the embrace of the US? Of course.

It is fair to say the society led by Fidel and now his brother, Raul, is not to American tastes. There are older Cuban exiles in Florida and elsewhere who will never forgive the Castros for their revolution. Equally, the stationing of Soviet missiles on Cuba in 1961-62 in response to the abortive Bay of Pigs invasion was hardly likely to endear Fidel to Washington.

Still: 54 years. Better than half a century in which Cuba created a socialist society (for anyone who did not dissent) while standing up to American bullying. The US stood alone in its own backyard - even loyal Canada refused to sever ties with Havana - and Cuba withstood every pressure. Its ramshackle 1950s cars became almost as iconic as its national health service. One result: infant mortality rates are better on the Castros' island than in America.

In the early 1990s, the US hoped the ending of the USSR's subsidies to Cuba would see a thorn removed from Washington's side. It didn't happen. Under President George Bush Snr, the US tightened its ­blockade with the - no irony implied - Cuban Democracy Act. This banned Americans from travelling to Cuba, prevented foreign-based subsidiaries of US firms from trading with Cuba, and even stopped family remittances to Cuba. It didn't work.

Now Barack Obama has said, finally, that enough is enough. In one sense, he is acting out the ­traditional role of second-term presidents who look abroad when the domestic scene is unrewarding. Given that his party took a hammering in recent elections and will be reduced to a minority in both houses of Congress when Republicans take control next month, Obama needs some luck if he is to leave that fabled "legacy".

So prisoners are exchanged and talks are begun to restore diplomatic relations. The White House will "review" Cuba's designation as a sponsor of terrorism. The travel ban on US citizens will be eased, as will restrictions on financial transactions. Most of America's allies have welcomed all of this, along with Obama's declaration that moves should begin to end the trade embargo. His problem is that only Congress can take that last and most important step. In other words, it will soon be time to see just how stupid Republicans really are.

Thus far, they have followed their customary rule of thumb: if Obama is for it, they're against. Currently, the temptation to depict the despised president as truckling to repressive communists is greater than any wish to consider America's interests or, for that matter, reality. Marco Rubio, the Cuban-American senator from Florida, has called the initiative a "dangerous and desperate attempt". Jeb Bush, latest of the tribe to fancy himself in the Oval Office, has deplored the sight of the US "negotiating with a repressive regime".

Hubris, in which Republicans have few peers, has induced the usual myopia. Just how has Cuba managed to withstand the blockade all these years, especially in the quarter-century since it lost Soviet support? Perhaps because the American superpower failed to notice that an embargo enforced by a single country - even a huge country accustomed to getting its own way - is as near to useless as makes no difference.

The US actions of the early 1990s outraged both the European Union and the United Nations General Assembly. All other major countries continued, and still continue, to trade with Cuba. Tourists, British tourists not least, travel eagerly to the island. The pariah in this is America.

What has been achieved? Five years ago, the embargo was costing Cuba $685 million (about £438m) a year amid periodic food shortages. The US Chamber of Commerce - opposed to the blockade, significantly - has since estimated it is costing America $1.2 billion annually in lost exports. Various think tanks have come up with figures up to four times that amount.

Meanwhile, Florida Republicans such as Rubio and Bush might have misread their constituents. Older Cuban-Americans might be furious with Obama, but his support among their community increased from one-third of the total in 2008 to better than half during his re-election campaign in 2012. In any case, according to a survey conducted in 2011, 80% of them no longer believe the embargo is working.

Republicans might get these facts into their heads in due course - they can ill-afford to lose still more of the Hispanic vote. On the other hand, the desire to frustrate Obama has trumped every alternative in the past. World opinion, even the Pope's opinion, is not likely to impress an insular crew if there is a chance to bring the country's first black president to heel. Raised on anti-communist crusades and versions of America First, these are not nature's internationalists.

There are risks in all this for Cuba, too. The US demand over 54 years has been for a reformed political system ("democracy") and, more important, for a rapid conversion to a free-market economic system. Cuba must open its doors, in short, to the multinationals, to globalisation, and to US finance. Even if the embattled island makes a free choice, it can probably kiss goodbye to its health and education systems, and much else.

This could include its decrepit charm, for one thing; its remarkable social solidarity for another; its status as a symbol of defiance against capitalism for a third. Perhaps, after half a century, it will have no choice. Capitalism's hired hands in America and elsewhere will be quick to pronounce communism, Cuba-style, a failed experiment.

They, in turn, will fail to answer a question: when was the experiment given a chance? The real point of the embargo was always to extinguish any risk of socialism 90 miles from America's shores.