The cable, which will one day improve Cuba's slow-paced Internet, was laid from a ship by the French company Alcatel-Lucent. It came in near the city of Santiago de Cuba in eastern Cuba, where Cuban officials including Vice President Ramiro Valdes awaited.
According to Prensa Latina, Cuban Information and Communications Minister Medardo Diaz said the cable was "a breach" in the longstanding U.S. trade embargo against the island, which Cuba has blamed for not having better Internet service.
He said it would "strengthen national sovereignty in telecommunications."
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The cable is a $70 million project financed by the left-wing regional group ALBA which includes Cuba and Venezuela.
It will not be connected until July and Cuban officials have said it will take time to link up the island due to poor infrastructure.
Santiago de Cuba is 540 miles southeast of Havana.
Cuban dissidents have accused the government of stalling Internet access because it wants to control the islanders' access to information.
But Deputy Information and Communications Minister Jorge Luis Perdomo said at a Havana conference this week there were no "political obstacles" to making the Internet more widely available.
When operational, the cable will provide download speeds 3,000 times faster than Cuba's current Internet and be capable of handling millions of phone calls simultaneously.
Currently, Cuba gets its Internet through a satellite connection that is slow and expensive.
According to government figures only 14 out of every 100 Cubans used the Internet in 2009, one of the lowest rates in the Western Hemisphere.
Another segment of the cable will be strung from Cuba to Jamaica, officials said.
(Reporting by Jeff Franks; Editing by Jackie Frank)
