Although U.S.-backed Syrian forces were able to retake control of a prison after Islamic State terrorists launched a sophisticated attack to free their brothers in arms, the jailbreak has raised concerns over what the dayslong assault means for the threat of ISIS going forward.

Focused on the Gweiran Prison in Hasakah, Syria, last Thursday, roughly 300 ISIS operatives detonated multiple car bombs before converging on the facility, Voice of America reported, citing the Syrian Democratic Forces. The facility housed roughly 4,000 ISIS fighters and another 700-850 boys and teenagers.