No / Pakistan's Directorate of Inter-Service Intelligence [ISI] plays an ambiguous role in the War on Terrorism. An important ally for Western intelligence with whom it has very close links, the ISI also has a long history of involvement in supporting and promoting terrorism in the name of Pakistan's geostrategic interests. This article explores the nature of the ISI and its aims and objectives in the post-9/11 era. It argues that the focus of the ISI's actions are to shore up Pakistan's ruling elite and to destabilize Pakistan's enemies by the promotion of Sunni Islamism at home and of pan-Islamist jihad abroad. The ISI's strategy, however, deeply conflicts with that of the West, a point underlined by the resurgence of Al Qaeda and the Taliban almost six years after the War on Terrorism began. With grave new trends evident in Pakistan, reliance on the ISI is failing and a Western rethink of its intelligence strategy toward Pakistan is now imperative.