At ninety years old, Saudi King Salman stepped from the shadows of governance this week to condemn Yemen's Houthi movement in terms rarely spoken by a monarch who has largely ceded daily rule to his son. His words — branding the group a 'terrorist militia' and their suspected targeting of Mecca a 'heinous crime' — carried the particular gravity of a man who speaks seldom but chose this moment to speak. The intervention reflects a kingdom confronting what may be its gravest security challenge in years: a conflict that has reached toward Islam's holiest ground and now threatens the energy corrid