The phones will run a modified version of Google's Android software being developed in a joint initiative by federal agencies and government contractors.
U.S. soldiers will be the first to receive the secure Android phones, sources within the project told CNN.
Several federal agencies are also expected to get phones for sending and receiving secure government cables while away from their offices, the sources said.
The Army has been testing such secure devices at U.S. bases for nearly two years, said Michael McCarthy, a director for the Army's Brigade Modernization Command.
About 40 phones were sent to soldiers overseas a year ago in a pilot project and the Army plans to ship 50 more phones and 75 tablets abroad in March, he said.
"We've had kind of an accelerated approval process," McCarthy said. "This is a hugely significant event."
Until now he United States has not allowed government workers or soldiers to use smartphones for sending classified messages because the devices have not met security requirements.