The Free Syrian Army (FSA) has announced it has moved its command centre for the first time from Turkey to areas inside Syria controlled by rebels.
A video posted on YouTube appears to show the army's leader, Riad al-Asaad, confirming the move.
It is not clear exactly when the move took place, or where in Syria the new headquarters are.
The FSA is the most prominent of the armed groups fighting to overthrow the regime of President Bashar al-Assad.
The BBC reports the move is significant as the FSA has previously been criticised for leading from Turkey and being out of touch with realities on the ground.
Meanwhile, Turkey's military has deployed armoured vehicles and heavy weapons to the border with Syria near a crossing that has seen intense fighting between rebels and government forces.
Local media say the deployment is in an area where earlier this week Turkish civilians were wounded when stray bullets and shelling crossed the border.