"The Gross family is devastated by the verdict and harsh sentence announced today by the Cuban authorities," defense attorney Peter J. Kahn said in a written statement. "Having already served a 15-month sentence in a Cuban prison, Alan and his family have paid an enormous personal price in the long-standing political feud between Cuba and the United States."
Kahn pledged to "continue to work with Alan's Cuban attorney in exploring any and all options available to him, including the possibility of an appeal." He has called for the contractor's immediate release on humanitarian grounds.
U.S. National Security Council spokesman Tommy Vietor quickly responded to Saturday's ruling, saying that it "adds another injustice to Alan Gross's ordeal."
"He has already spent too many days in detention and should not spend one more," Vietor said. "We urge the immediate release of Mr. Gross so that he can return home to his wife and family."
Gross' wife, Judy, attended the trial with her attorney. Three U.S. officials also attended as observers. His mother has recently been diagnosed with lung cancer and their daughter is recovering from a double mastectomy.
Gross has been held at the high-security Villa Marista prison after being detained at Havana's international airport in December 2009.
U.S. Secretary of State Hillary Clinton told reporters Friday that Gross had been "unjustly jailed for far too long."
"He needs to be able to leave Cuba and return home," Clinton said. "This is a matter of great personal pain to his family and concern to the U.S. government."
His detention and subsequent sentencing have brought an apparent standstill to tentative efforts by both countries to overcome years of hostility.
Gross had been working for Development Alternatives Incorporated, a Maryland-based subcontractor that received a multimillion-dollar U.S. contract for democracy-building efforts on the island nation.