It’s a looming heavyweight prizefight that nobody wants to see come off. But should escalating tensions between bitter regional rivals Iran and Saudi Arabia break out into open conflict, Riyadh’s formidable military arsenal would quickly overwhelm Iranian forces in a conventional war, while Tehran would hold the advantage against any Saudi forces in a proxy guerrilla war, analysts say. The animosity between the two main pillars of power in the Middle East has escalated over the past week, when Saudi Arabia’s foreign ministry ordered all Saudi nationals to immediately evacuate Lebanon. The move was presumably targeted at the growing power...