Today, the U.S. Marines kicked off a new push against bad guys in Afghanistan's fertile and poppy-rich southern province. Per the AP:

Gen. David Petraeus says the Marine Corps offensive launched Friday in southern Afghanistan is part of preparations for the arrival of 30,000 new U.S. reinforcements.

Petraeus told The Associated Press that the military has been working for months to extend what he called "the envelope of security" around key towns in Helmand and Kandahar provinces....

U.S. Marines swooped down behind Taliban lines Friday in the first offensive since Obama announced the surge.

About 1,000 Marines and 150 Afghan troops were taking part in a bid to disrupt Taliban supply and communications lines in the Now Zad Valley of Helmand province in southern Afghanistan.

But there's a mystery lurking behind this new demonstration of military pluck, which is why, exactly, we're placing so much focus on sparsely-populated Helmand to begin with. Smart people from different sides of the debate--ranging from COIN guru John Nagl ("I didn’t understand putting the first troops into Helmand this summer," he told Noah Shachtman this week) to Senator Carl Levin ("we have enough troops in Helmand right now," he groused on  Tuesday)--have been asking that question, and I have yet to see a clear and direct answer.

Props to Time's Joe Klein, by the way, who predicted back in September that one ill-advised escalation in Helmand (Klein argued that the troops would have been better sent to secure the vital population center of Kandahar) would inevitably beget more:

What can be done now? The military will want more troops to paper over its strategic mistake. It will resist any suggestion to leave Helmand and redeploy to Kandahar. "That would be a death sentence for all the people in Helmand who have supported us," a military expert told me

Which is not actually a terrible reason, you have to admit, although it's a hard thing to explain to a fallen soldier's grieving family.