The conflict took a serious regional turn in November 2009 when the Saudi military launched an anti-Houthi offensive. Hundreds of Houthi rebels and Saudi troops were killed in the fighting. Riyadh was alarmed by the prospect of an Iranian-backed Houthi autonomous region springing up along its border, not only because of the ramifications of such a prospect for the Saudi–Iran balance of power in the Persian Gulf region, but also because of its direct implications for the kingdom’s stability.