Houthi attacks and no Western support: What are Saudi Arabia's options ?

The US has warned that fighting between Saudi Arabia and Iran-backed Houthis could rapidly escalate. It comes after a missile attack targeted Riyadh for the first time since the Yemen conflict resumed. The Houthis' lightning offensive seized swathes of Yemeni territory in recent weeks and has left hundreds dead. In the face of such attacks and with no support from its American ally, what are Saudi Arabia’s options?