Yemeni fighters from the Houthi movement said they will seal off Saudi Arabia’s coast starting Monday. Their spokesman, Yahya Saree, described it as naval attack. Merchant ships moving through the Red Sea near Saudi ports might see postponements. U.S. warplanes continued striking targets after their warning. The group captured several ships. Insurers now see Red Sea routes as dangerous. Traders are watching closely, watching for higher fees or diverted shipments. Saudi ports border the danger zone, so any slowdown matters fast.