Syrian activists and state media said Tuesday government troops broke a nearly three-year siege by Islamic State militants on the eastern city of Deir el-Zour.
The reports said the troops reached a key government air base on the western edge of the city.
After Syria's 2011 uprising, rebel groups and jihadists seized Deir el-Zour and the province by the same name. Islamic State fighters took command of the region by 2014.
Estimates of the number of people living in the city vary widely, with the Syrian Observatory group saying the population has shrunken to about 150,000, half what it was before the outbreak of the Syrian civil war.
Deir el-Zour is major prize for Syrian President Bashar al-Assad since it is the center of the country's oil industry. As Syrian forces have advanced east in recent months, the government has regained control of oil and gas fields.