US military chief Admiral Mike Mullen called the Pakistani military leadership and assured them that Washington respected Pakistans sovereignty and territorial integrity. The calls were made after Pakistan lodged strong protests against a series of attacks by the US-led International Security Assistance Force during the last three days, and conveyed to the United States that if forces in Afghanistan continued to violate its territorial integrity it would be forced to consider appropriate response. At Pentagon, spokesman Col Dave Lapan told journalists that recent cross-border air strikes by Nato helicopters in Pakistan might have violated procedures and resulted from communication breakdowns.I dont know that Id call it a disagreement but there are certainly discussions under way between our forces and the Pakistanis about this particular incident, he said. Col Lapan said the talks were focused on what were the communication breakdowns, what happened, what was supposed to happen.Isaf forces were not able to notify Pakistani officers about the helicopter strikes until after the operation, he said.I think I can say that clearly in these instances things didnt occur in the way that theyre supposed to. And thats what were trying to get to, Col Lapan said.Isaf said in an earlier statement that the helicopters went after insurgents in Pakistan after an Afghan security forces outpost in the Khost province came under attack on Friday.Diplomatic sources in Washington told newsmen that Pakistan had informed the Americans that while Islamabad was Americas partner in the war against terror, they are very sensitive to their sovereignty and territorial integrity. The Pakistanis insisted that the UN and Nato mandate for operating inside Afghanistan ended on the Afghan border and it does not cover an inch of Pakistani territory.The Pakistanis said that they were still investigating the three incidents to see if the helicopters fired their weapons from the Afghan territory or physically entered Pakistan.