For the 40 years since Fidel Castro's revolution, successive US administrations have tried to oust Cuba's Communist government.

One of the main bones of contention between the two countries is the US naval base at Guantanamo Bay - on the eastern end of the island.

The base was established under a treaty signed a century ago - and the Cubans want it back.

Cuban watch on the border

The line between the base and mainland Cuba, marked by barbed wire and minefields, is one of the last cold war frontiers.

From his watch tower, Captain Lobaina and his soldiers from the Cuban army spend much of their time watching US troops across the line practice firing mortars.

"Our job is to observe anything they do inside the base," he said. "We have to make sure no-one comes out and that no Cubans try to break in from this side. Imagine how we feel about the base. Part of our national territory has been usurped."

The base occupies one of Cuba's best natural harbours. The contrast with the nearby Cuban town of Guantanamo, where most people earn less than ten dollars a month, is stark.

Before Fidel Castro's revolution in 1959, the base employed several thousand people from the small town.

While most lost their jobs during the first cold war tensions, a few were kept on and their $1000 monthly salary is now worth a small fortune.

Selvin Fairweather: seen four decades of conflict

Selvin Butler Fairweather is one of them. Through the last four decades of conflict he has left his home in Communist Cuba every morning, travelling in a special bus, through the frontier post to the naval base of his country's great enemy.

"I started to work on the naval base as a fire fighter. I am now in a supply department of the US navy. They are Americans and we are Cubans - their culture is different. So when we are over there we are thinking one way and when we cross that gate and come over here we are someone else," he said.

Tensions at the border have certainly diminished since the worst cold war days.

The Cuban Frontier Battalion, set up to confront the US troops in the base, no longer expects imminent US invasion and the US military no longer sees the Cuban army as a threat.

Cuban refugees on the border

For the past decade the battalion has spent more time stopping Cubans trying to get into Guantanamo - as thousands did in 1995 with many dying in the mine fields.

In one of the few areas of formal co-operation between the two countries, those attempting to get to the US via the base are now sent back.

Tensions at the line have diminished to the extent that the Cubans are expanding tourist facilities around the base. A restaurant and bar are being built on a lookout high above it.

But Colonel Gramalier Crespo, who is in charge of the Cuban frontier battalion, says there is a limit to the co-operation.

"We have been able to improve day to day relations - to stop provocations around the base. But the problems between our countries are deeper.

Watchtowers symbolise the blockade

"We have been struggling for 40 years to get the United States to remove their economic blockade. There are still barriers," he said.

The 14 remaining Cuban workers on the US base, the youngest of which has just turned 69, will retire soon to pensions paid by the US treasury. They live in hope that Cuba and the US will one day mend their differences.

"We did live together at one time, before this problem. But it just can be solved any time. There's no big thing in there. And maybe when this become normal I won't be around because I'm over now. I'm 70. I should be retired at 65," he said.

While the conflict continues - no new Cuban workers will be hired at the base. But if it ends the days of the base itself - where personnel have already been cut right back - may well be numbered.

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