Pak air defence on the border

The Pentagon and the Pakistani military have denied a pair of reports that emerged September 15 that said Pakistan had repelled US air incursions. Even before the reports, tensions have been on the rise between Washington and Islamabad, creating the potential for military encounters in the air over the Afghan-Pakistani border region, reports Stratfor.com.
Pakistani sources told a foreign news agency on Sept 15 that US helicopters were fired upon by Pakistani troops near Angoor Adda in South Waziristan, and turned back while attempting to cross the border under the cover of darkness. The same day the Pakistani media reported that Pakistani fighter jets had scrambled and intercepted a US 'spy plane' (this could have been an unmanned aerial vehicle) in or near North Waziristan that then returned to Afghanistan.
Regardless of the truth to these now-denied claims, the chance that rising tensions between Washington and Islamabad may manifest themselves in the form of military encounters in the air above the Afghan-Pakistani border region is indeed cause for concern.
Islamabad is trapped between the need to get control over its own jihadist uprising and the need to show its domestic population that it is standing up to increasingly overt unilateral US military action inside its territory. Opposing the primary vector of these actions - unmanned aerial vehicles (UAVs), fighter jets and helicopters - is one way Pakistan can attempt to push back against the United States and demonstrate its resolve to both Washington and its own people, whether it chooses to do so overtly or through proxies.
The nature of US intelligence, surveillance and reconnaissance (ISR) and special operations forces operations in Pakistan makes it difficult to effectively defend against, however. Constant monitoring by UAVs, bombings by aircraft from along the border and lightning late-night raids across the border in high terrain present a number of defensive challenges in an area where Islamabad already struggles to enforce its writ.