The Houthis have been at war with the Saudi for some time now.
The Saudis have been using up the spare parts that had been sold to them in the 70s by a Bird Colonel I knew in the Pentagon who was vying to be the world's leading arms merchant.
Nothing surprises me about the backstabbing that goes on in the Middle East. ;)
"When bad men combine, the good must associate; else they will fall, one by one." Edmund Burke