Was just completing the new electronic application process now required for visas to USA under the Visa Waiver Program.
In the Q's & A's was the following.......in a sense nothing new ...entry is always up to the US official but interesting all the same
Q Am I allowed to visit the United States after I've been to Cuba?
A Entry (even with a valid visa) is determined by U.S. Immigration officials at the port of entry. You may wish to take supporting documents about the purpose of your trip.

