As it continues to juggle balls through seemingly never-ending foreign policy crises, the Obama administration finally has brought one safely to ground, at least temporarily.

The historic agreement reached Sunday with Iran marks a decisive moment in U.S.-Iranian relations and a potentially significant achievement for the administration. But the deal comes at a time when President Barack Obama and his energetic secretary of state still face a panoply of diplomatic challenges in the Middle East — some of which may now get even harder.

In Syria, where U.S.-backed negotiations to end the civil war have been scheduled and canceled half a dozen times since the spring, the parties on the ground seem less amenable than ever to a diplomatic solution, and Washington and Tehran remain on opposite sides.