Qatari and Pakistani mediators are working on an interim deal: an end to attacks on shipping in exchange for lifting the US blockade of Iranian ports.
A new front has opened in southern Yemen in Lahij province. Saudi strikes killed at least 17 people in two days, according to the Houthis, while Riyadh says it thwarted another drone attack on Mecca.
Three ballistic missiles hit a training centre in al-Alam camp north of Ataq. Presidential Leadership Council head Rashad al-Alimi called it a terrorist attack.
An offensive that began near Taiz on September 3 has brought the Houthis to the Red Sea coast. Unverified reports also speak of the capture of the Hanish Islands.
Trump ordered "decisive and powerful" military action and warned Iran to stop supporting the Houthis. The Houthis vow to respond.
Strikes on radars, storage sites and launch positions came ten days after the first joint operation. The Houthis continue to attack ships in the Red Sea and the Gulf of Aden.