In a saucepan, combine the water and sugar. Heat over medium heat, stirring until the sugar is dissolved. Do not boil.
Remove the saucepan from the heat. Add the tea bags and fresh or frozen cherries. Let steep for 5 minutes.
Remove the tea bags and discard. Strain the liquid through a fine-mesh sieve into a pitcher, pressing gently on the cherries to extract as much juice as possible. Discard the solids.
Stir in the cherry juice, if using. Let the mixture cool to room temperature, then refrigerate for at least 1 hour, or until thoroughly chilled.
To serve, fill glasses with ice. Pour the chilled cherry iced tea over the ice. Garnish with fresh mint sprigs and cherry halves, if desired.
Notes
For a sugar-free version, use your favorite sugar substitute or omit the sugar and rely on the natural sweetness of the cherries and cherry juice.