U.S. President Barack Obama and Turkish Prime Minister Recep Tayyip Erdogan have spoken by telephone "to coordinate efforts to accelerate a political transition in Syria."
A White House statement says the transition "would include the departure" of Syrian President Bashar al-Assad, and would "be responsive to the legitimate demands of the Syrian people."
The telephone conversation between the leaders on July 30 came as the United Nations said tens of thousands of people are fleeing a worsening battle in Syria's most populous city, Aleppo.
Meanwhile, U.N. Secretary-General Ban Ki-moon said a convoy transporting the head of the UN monitoring mission in Syria, Babacar Gaye, was attacked on July 29 by Syrian army tanks.
In London, Syria's most senior diplomat defected on July in protest against what he called the "violent and oppressive" acts of Assad's regime.
Based on reporting by Reuters, AP, and AFP