The U.S. ambassador to Turkey condemned a car bombing in Istanbul on Tuesday that killed 11 people and wounded 36 more as a terror attack, adding that Washington stood "shoulder to shoulder" with its NATO ally.

"Deeply saddened by the barbarous terror attack in Istanbul. Such senseless violence could never be rationalized by any cause," John Bass wrote on Twitter. "We condemn this heinous attack, and continue to stand shoulder-to-shoulder with Turkey in the fight against terrorism."