Iran is secretly helping Syrian President Bashar al-Assad put down pro-democracy demonstrations, according to U.S. officials, who say Tehran is providing gear to suppress crowds and assistance blocking and monitoring protesters' use of the Internet, cellphones and text-messaging.

At the same time, communications intercepted by U.S. spy agencies show Tehran is actively exploring ways to aid some Shiite hardliners in Bahrain and Yemen and destabilize longstanding U.S. allies there, say U.S. officials familiar with the intelligence....