Karzai's relations with neighboring Pakistan were good, especially with the Awami National Party (ANP) and Pakistan Peoples Party (PPP). He often describes his nation and Pakistan as "inseparable twin brothers", a reference to the disputed Durand Line border between the two states, despite the many border skirmishes that occurred during his presidency. In December 2007, Karzai and his delegates traveled to Islamabad, Pakistan, for a usual meeting with Pervez Musharraf on trade ties and intelligence sharing between the two Islamic states. Karzai also met and had a 45-minute talk with Benazir Bhutto on the morning of 27 December, hours before her trip to Liaquat National Bagh, where she was assassinated after her speech. After Bhutto's death, Karzai called her his sister and a brave woman who had a clear vision "for her own country, for Afghanistan, and for the region – a vision of democracy, prosperity, and peace." In September 2008, Karzai was invited on a special visit to witness the swearing-in ceremony of Asif Ali Zardari, who became the President of Pakistan. Relations between Afghanistan and Pakistan have improved after the PPP party took over in 2008. The two nations often make contacts with one another concerning the war on terrorism and trade. Pakistan even allowed NATO forces stationed in Afghanistan to launch attacks on militant groups in Pakistan. This was something strongly opposed by the previous government of Pakistan. The two states finally signed into law long-awaited Afghanistan–Pakistan Transit Trade Agreement in 2011, intended to improve trade. Karzai acknowledges Pakistan's meddling in Afghanistan's wars, but said in a 2015 interview that Afghanistan wants a "friendly relationship but not to be under Pakistan's thumb."