Along the western edge of the Arabian Peninsula, a conflict long simmering beneath the surface of a fragile truce has broken open again. Yemen's Houthi rebels claimed Saturday strikes on Riyadh and the port city of Yanbu, setting a fuel depot ablaze near Saudi Arabia's main international airport and disrupting the rhythms of civilian life in the capital. The attacks, framed by the Houthis as retaliation for Saudi strikes on Sanaa, mark a new threshold in a war that has now extended its reach from contested Yemeni territory into the heart of Saudi infrastructure — and onto the waters of one of