Hamid Karzai is lonely. He is huddled, as always, deep inside his presidential palace in Kabul, protected by towering stone walls, growling dogs and U.S. bodyguards. Visitors to the palace must undergo three separate body searches before passing through the arched gates, all under the gaze of trained marksmen standing sentry in a watchtower.
On this day in February, a driving blizzard has made Karzai's lair seem even more forbidding. Only one person gets through unchallenged: Zalmay Khalilzad, the U.S. ambassador to Afghanistan. Inside Karzai's office, the two men converse in English and Dari, one of Afghanistan's two official languages. Karzai,...