The conflict has opened a second front in the Middle East after the United States and Israel attacked Iran, adding to global uncertainty and turmoil in energy markets.
The Iranian-backed militia was engaged in fierce battles with Saudi-backed government forces in Yemen on Sunday, as it seeks to maintain momentum in the war.
Smoke rising from the fuel storage depot at King Khalid International Airport in Riyadh, Saudi Arabia, on Saturday. The Houthis said they had launched missiles and drones at the Saudi capital.
U.S. intelligence agencies have warned in internal reports that China could acquire or steal U.S. warplane technology if F-35 jets are sent to Saudi Arabia.
If the production and delivery of the planes is completed, which would take years, Saudi Arabia would be only the second country in the Middle East to have F-35 jets, after Israel.