Pakistan ? Pakistani ground troops moved into Taliban-controlled areas Friday and engaged in the first gunbattle of a new offensive in the volatile northwest, as an aerial and artillery bombardment pounded other targets.

Officials said Friday’s action did not represent the start of a full-scale operation in the tribal belt along the border with Afghanistan, but that most troops were now in place for when the orders came.

The coming operation in South Waziristan, along with one winding down in the Swat Valley further north, could be a turning point in Pakistan’s yearslong and sometimes halfhearted fight against militancy.

Washington strongly supports the operations, which are seen as a test of nuclear-armed Pakistan’s resolve against an insurgency that has expanded in the past two years.