Washington and Moscow flooded the Korean Peninsula with arms and aid as they fueled the war between South and North seven decades ago. Now, in a fateful moment of history turning back on itself, Russia and the United States are reaching out to those same allies to supply badly needed munitions as the powers face each other down again, this time on the other side of the globe, in Ukraine. When Russian President Vladimir Putin met North Korea’s leader, Kim Jong Un, in Russia’s far east Wednesday, they struck what North Korea called “a satisfactory agreement” on “the immediate cooperation...