Yemeni fighters from the Houthi movement said they will seal off Saudi Arabia’s coast starting Monday. Their spokesman, Yahya Saree, called it a maritime strike. Merchant ships moving through the Red Sea near Saudi ports might see postponements. U.S. warplanes kept hitting objectives after their warning. The group seized several ships. Insurers now see Red Sea routes as dangerous. Traders are holding their breath, watching for extra costs or diverted shipments. Saudi ports sit near the risk area, so any slowdown matters fast.