The implications of the Yemeni crisis on Saudi national security, as well as the entire Gulf region, are tremendous. The prospects of an Iranian-backed and allied Shia militia taking over Yemen at the tip of the Arabian peninsula was a clear red line for the Kingdom. With army brigades loyal to former Yemeni Ali Abdullah Saleh joining the Houthis in removing the legitimately elected President Abed Rabbo Hadi from power, and attempting to seize major Sunni urban centres such as Aden and Taiz, the Saudi leadership had no alternative other than to act, and act decisively.