http://www.slate.com/id/2233153/Fred Kaplan writes good common sense about what went on behind-the scenes.
Sen. John Kerry's successful mission to Kabul—in which he convinced Afghan President Hamid Karzai to hold a second-round runoff to August's fraud-soaked election—suggests that the Obama administration is putting the squeeze on Karzai to clean up his act as a precondition to getting more U.S. troops to help fight his war.
The squeeze was subtler—or, at least quieter—than the yelling sessions that AfPak envoy Richard Holbrooke and Vice President Joe Biden—both famously voluble characters—have held with Karzai in recent months...
...Enter Kerry, who can be viewed as a somewhat independent player—close to, but not formally a part of, the Obama administration—whose style is the farthest thing from brash.
Politically, Karzai cannot afford to look as though he's buckling to foreign pressure. If he goes along with a runoff election, he has to make it seem that the decision was his alone. Pressure from an outside power can work only if it's applied with discretion and respect. Kerry, who was on a trip to Afghanistan and Pakistan anyway, was the right man for the mission...
Lots more at the link.