Transcript for US warns against travel to Cuba

says he will continue to investigate this. Cuba warning Americans not to visit there and ordering more than half of its staff to return home. After those mysterious attacks. ABC's Martha Raddatz with what she's learned. Reporter: The mystery is so deep, the health effects so serious, that tonight the state department is ordering all non-essential embassy personnel and all embassy families to leave Cuba, and warning Americans to avoid travel to Cuba. The state department also suspending all routine Visas to the U.S. Issued in Cuba. Very bad things happening in Cuba. Very bad things. Reporter: The attacks, including sonic harassment, began late last year, more than 20 diplomats targeted in their homes and Havana hotels. Reports of permanent hearing loss, confusion, loss of balance, and mild traumatic brain injury. One victim reportedly jolted from bed by a "Blaring, grinding noise," but just a few feet from the bed -- silence. It was like passing through an invisible wall with an invisible assailant. We don't know who is responsible. We don't know what is responsible. Reporter: Officials say they can't rule out that Cuba, Russia, or some other third party is behind the attacks. Today jetblue responded to the travel warning saying they would waive any cancellation fees if customers have any hesitation about visiting the island. But so far no tourists have been targeted in these mysterious attacks. Martha Raddatz who continues to follow the mystery in Cuba. Still much more on "World news

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