PML(N) chief Mian Nawaz Sharif said that he has nothing personal against President Asif Ali Zardari, adding that his differences were based on principles. Speaking to reporters after meeting with US officials here on Tuesday, he said: I have categorically shared my stance with US officials. He said drone attacks in tribal areas by US forces are 'counterproductive. US President Barack Obama will have to change its policy about drone strikes, he commented. Two-time prime minister stressed that the whole nation needed to unite to deal with the prevailing challenges. To a question, he said that he has no intention to rejoin federal cabinet. It was partys decision to part ways with the federal government.