We've had multiple central fronts in the War on Terror. We've had various decisive blows against al-Qaeda. Now the US military has come up several centers of al-Qaeda gravity: Baghdad, where the Surge was concentrated, but also northern Iraq, where the bad guys are concentrated --
"Mosul is the center of al-Qaida's terrorist activities today. Mosul is a critical crossroads for al-Qaida in Iraq. Baghdad has always been al-Qaida's operational center of gravity, but Mosul remains their strategic center of gravity as it provides access to the flow of foreign fighters," [US Navy Rear Admiral] Smith said.
Mosul is located at the locus of roads that connect Iraq with Syria to the west, Turkey to the north and Iran to the east. Many fighters smuggled in from Syria make their way through Mosul, where they can easily blend in with city's ethnically and religiously diverse population.
"It is their strategic center of gravity. One-half to two-thirds of attacks in Iraq today are in and around Mosul," Smith said.
Of course one problem with these centers of gravity is that the US attempts to chase them brings the opposite polarity (to botch the physics metaphors) and the centre of gravity moves. Does John McCain really think this futility will not be an issue in the November election?
Incidentally, the news story linked above has a little detail at the end symbolic of the quagmire. A US helicopter fired at teenagers digging at a roadside in the belief they were planting a bomb. They were looking for roots to burn as fuel. In oil rich Iraq.