Whatever weaponry is left over after Assad falls will almost certainly be aimed at Israel.

BEIRUT (AP) — Syrian rebels strengthened their hold Thursday on an oil-rich province bordering Iraq, activists said, capturing a key military base that was considered one of the last bastions for President Bashar Assad’s loyalists in the strategic region.

The reported fall of the Mayadeen base, along with its stockpiles of artillery, caps a series of advances in Deir el-Zour including last week’s seizure of a military airport.

The province borders on western Iraq. Syria’s rebels enjoy strong support with the Sunni tribes of Iraq’s west, and many Iraqis with combat experience from their own war are believed to have crossed to fight in their neighbor.

Rebel fighters also say that weapons seized when bases fall have been essential to their transformation from ragtag brigades into forces capable of challenging Assad’s professional army.

Activist groups and a local fighter told The Associated Press the Mayadeen base was taken in the morning hours, after a three-week siege. The fighter spoke on condition of anonymity because of security concerns.

Violence also was reported in opposition strongholds around the capital Damascus and in the northern city of Aleppo, where government aircraft damaged one of the rebels’ key field hospitals.