Wherever Can The Mystery Money Be Coming From?

Today's Washington Post reports that US officials are befuddled to learn that millions of dollars in cash are leaving Afghanistan every single day for Dubai. As long as the dough is declared at customs, it's legal in Afghanistan, and Dubai sure isn't grousing about the windfall for its banking system.

At last summer's rate, over a billion dollars left Afghanistan last year. The government's total annual revenue (not counting foreign aid) from taxes and other income was only $875 million. And that billion is only the moolah declared at customs! US officials have no idea how much more is headed out unrecorded on the six daily flights from Kabul to Dubai.

The article's whole hook is how clueless the US is about where this money is even coming from. Is it Saudi funds for building madrassas being embezzled? Is it (only the briefest mention) drug profits from the country's flourishing opium and heroin exports (I diaried about this a couple months back)? Is it being smuggled in from Pakistan???

Oddly, neither the article nor any of the unnamed US officials quoted seem to think it could be, in whole or part, embezzled US aid money--civilian or military. The article also does not have any Afghan-in-the-street quotes. Whaddaya wanna bet that savvy residents of Kabul might be able to dispel some of the mists of uncertainty enveloping US officials there?