Noah Shachtman and Spencer Ackerman identify it:
For all the handwringing about the undeclared, drone-led war in Pakistan, it’s quietly been eclipsed. Yemen is the real center of the America’s shadow wars in 2012. After the US killed al-Qaida second in command Abu Yahya al-Libi earlier this month, Pakistan is actually running out of significant terrorists to strike. Yemen, by contrast, is a target-rich environment — and that’s why the drones are busier there these days.
The Dish 