Trump’s Iran war has already taught Russia and China some valuable lessons.

Sign up for the Slatest to get the most insightful analysis, criticism, and advice out there, delivered to your inbox daily. President Trump’s war on Iran is turning out to be an even bigger calamity than it seemed just a few weeks ago. Not only has he proved unable to convert America’s vastly superior military power into any sort of geopolitical victory, he has also weakened our position worldwide. The consequences of this erosion are likely to be longer-lasting than the (considerable) economic impact of Iran’s shutdown of the Strait of Hormuz, the narrow transit for a quarter of the…