Yemeni Houthi fighters ambushed a Saudi Army position in the bordering Saudi region of Jizan on Thursday, taking advantage of the thick fog.
A published video of the successful ambush attempt shows a handful of destroyed Saudi Army vehicles and trophies taken by the infiltrators.
The infiltration comes days after a Saudi Al Madinah-class frigate targeted by anti-ship missile off the coast of Yemen.
The Jizan Region is the second smallest region of Saudi Arabia. It stretches some 300 km along the southern Red Sea coast, just north of Yemen.