Why are Houthi missiles breaking through Saudi Arabia’s air defences?

Yemen’s Houthis, the armed group also known as Ansar Allah (Arabic for Supporters of God), are hitting deep inside Saudi Arabia with waves of ballistic missiles, cruise missiles and drones.

Riyadh’s King Khalid International Airport has been targeted multiple times by the Houthis since their new military campaign against the kingdom began in September.

An attack on the airport on Saturday ...