Setting an exact default date is difficult, if not impossible, because the government’s day-to-day finances are dictated by a wildly unpredictable cocktail of political, economic and natural forces. Here are a few hypotheticals that could buy Congress more time—or bring on default more quickly than anyone saw coming.

Syria

Few events wreak more havoc than military interventions. Federal budgets, of course, do not come away unscathed. And right now, it’s looking like there’s a decent chance there will be some form of U.S. intervention in Syria.

Such an intervention, even if its just a targeted missile strike, could cost the U.S. billions, and alter the debt-limit timeline. In July, Joint Chiefs Chairman Gen. Martin Dempsey told Congress that the cost of targeted strikes against Bashar al-Assad’s military “would be in the billions,” and that just instituting a no-fly zone over the country would cost about a billion dollars a month.