Pakistan has been using border crossing closures for political signaling, restricting transit to Afghanistan to convey its message that armed helicopter flights in Pakistani airspace cross the line of tolerable US actions. The September 30th helicopter incident and its aftermath have significant implications. First is that the US has found a red line that Pakistan cannot afford to let the US cross. Second, mistakes from drone attacks are more forgivable than helicopter attacks. And third, the Taliban will learn that a week-long cut-off of supplies at border crossing points is enough to spur action by the US to have the border reopened.