"We will send military resources, that is, soldiers, radar and defence systems," French President Emmanuel Macron said in a French television interview.
Britain has previously promised military support to Saudi Arabia, including a British tanker aircraft to assist with aerial refuelling of Saudi fighter jets.
On Saturday, the Houthi movement attacked the Saudi capital, Riyadh, for the first time in years. The attack was described as a major escalation of the conflict.
The port of Yanbu is important for Saudi oil exports.
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