Chalk one up for US ingenuity

I was just reading the CNN homepage a few hours ago, and noticed this picture of some soldiers standing in front of a sign in Kabul, Afghanistan:


AP photo from Kabul (original can be seen here)
I cursorily noticed the sign, then saw that it had some text, and then read the text and thought to myself, "Hmm, that's a well-done sign. It promotes a positive outlook, and tries to engender a feeling of togetherness in the people." Then I realized that, wait a second, that sign is in Afghanistan.

A quick check of the CIA World Factbook confirmed my suspicion: the languages spoken in Afghanistan are "Pashtu (official) 35%, Afghan Persian (Dari) 50%, Turkic languages (primarily Uzbek and Turkmen) 11%, 30 minor languages (primarily Balochi and Pashai) 4%, much bilingualism."

So, why is there a giant banner sitting in the middle of Kabul written in a language that few of the local residents can read?

(more pictures of the same banner can be seen here, here, and here)

[Update: Sepoy comments, both here and at BoingBoing, that the banner is apparently by Afghan Wireless, and is likely one of a common genre of signs (and ads) produced by companies congratulating the newly elected leader. Still doesn't explain why it's in English, however.]