Dissident blogger Yoani Sanchez, an advocate for wider Internet dissemination, questioned whether the government would have said anything about the cable if Renesys and foreign media had not reported about it.
"(Hashtag) Granma says now it's necessary to build infrastructure for the (hashtag) FiberOpticCable to provide service!" she tweeted. "And what were they doing the past two years?"
Cuba has the second-worst Internet connectivity rate in the world, according to one study.
According to government statistics, about 16 percent of islanders have some online access, usually through their school or workplace and often just to an Intranet that also has email capability.
Just 2.9 percent of Cubans report having full access to the World Wide Web. However outside observers say the true number is more like 5 to 10 percent accounting for underreporting of dial-up minutes resold on the black market.
Peter Orsi on Twitter: www.twitter.com/Peter_Orsi