Senior rebel officials in the Syrian province of Idlib have reportedly said  this week that Turkey is boosting military aid to opposition fighters in hopes of countering a Syrian government offensive.

The arms supplies have come following Turkey’s recent summit meeting with Russia and Iran, who are backing Syria’s attempt to retake the region, according to Channel News Asia, which reported the officials’ comments.

The stakes are high for Turkey, which is already providing refuge for more than 3 million Syrian refugees. Syria’s northwest is home to another 3 million people, many of whom have fled there from other cities.

Outside observers, ranging from humanitarian groups to foreign governments, have warned that the expected attack on Idlib could be the most bloody of the long civil war, considering the number of people trapped in the province.

“They pledged complete Turkish military support for a long, protracted battle,” said one senior Free Syrian Army commander, who took part in talks with Turkish officials. The official requested anonymity as he was not authorized to disclose the information.

“These arms supplies and munitions will allow the battle to extend and ensure our supplies are not drained in a war of attrition,” the commander added.