High-level diplomacy has intensified among competing Middle East regional powers, a flurry of bilateral talks that increasingly suggests what a “Plan B” would look like if, as seems likely, the U.S. and Iran fail to revive the deal that briefly constrained Tehran’s nuclear program. The pace of contacts and meetings …

Observers in Washington and European capitals who were worried about NATO’s nuclear deterrent breathed a sigh of relief in late November, when the new German governing coalition signaled it would continue Germany’s role in the alliance’s nuclear-sharing agreement. But their reaction was tempered by the uncertainty that still surrounds U.S. …

There are any number of ways to measure one of the great secular transformations of our time: the decline of the United States’ power relative not only to a rising rival like China, but to the rest of the world generally. From 1960 to the present, the American share of …