By Stephen Evans
BBC North America business correspondent

The American trade embargo on Cuba has always had as much to do with politics as economics.

The rationale is that depriving the Castro regime of dollars from tourists or goods from American factories will turn up the pressure on the leader himself, hastening his downfall.

On 30 June, the embargo is tightened further. The Bush administration has ruled that Cuban-Americans can only go home once every three years instead of every year.

When they get there, they will only be allowed to spend $50 a day, down from $167.

They will also need a special licence stipulating that they can only visit immediate members of their family.

Limits on how much money Cuban-Americans can send back to the island from the United States are lowered too.

'Kiss of death'

The Bush administration is also increasing its spending on various anti-Castro propaganda measures, like boosting signals from American, anti-Castro radio and television stations and giving more money to exiled dissident groups.
 

Will it work? The Los Angeles Times thinks not.
"Offering $36 million to Cuban dissidents is tantamount to giving them the kiss of death," the paper said.

"They would immediately be labelled 'agents of the American imperial power' and probably imprisoned.

"Castro will be 78 in August. Come January, he will celebrate his forty-sixth year in power. Ten US presidents have tried to oust him and failed.

"This administration, strapped for cash to keep out terrorists and conduct the war in Iraq, ought to at least stop the bleeding of taxpayer dollars on such low-return enterprises," cried the paper.

New political rules

It seems the economic consequences of tightening the noose on Cuba are likely to be less than fatal to the regime in Havana.

It also seems likely that the political consequences for the administration in Washington will be less than beneficial.
 

There is an old piece of conventional wisdom that may turn out to be plain wrong.
The common belief used to be that the harder Washington makes it for Castro, the better it will play in Florida - and Florida is a place where the White House needs its policies to play well.

It remains true that there is an influential group of Cuban exiles who have weight in Republican circles and who lobby for tighter and tighter restrictions on travel to and trade with the island.

But there is also now a younger group who don't take such a hard-line stance. They certainly don't like Castro, but they also value contact with their families on the island.

They want the regime to fall but they don't yearn for it with every fibre of their bodies like their grandparents who have active memories of life on the island.

Political backlash

Many Cuban-Americans are angry at the new restrictions. Travel agents have been scrambling to re-arrange trips before the new regulations come into force this week.

The change has been so sudden that some travellers may find themselves in Cuba on the old papers, unable to leave.
People are complaining in Florida that they have sick relatives back in Cuba and they need to see them more than once every three years.

This is not going to send the Cuban-American community in Florida into the booths to vote for John Kerry in droves, but it may be enough to tip a few of them away from Mr Bush.

And it shows how politics and economics aren't quite playing as they used to.

There are no hard and fast rules about economic embargoes: tightening trade with the Soviet Union and Libya may well have hastened change, but in Cuba there's not much evidence of that yet.