He built Pakistan's nuclear bomb and is accused of having sold his knowledge to Libya and Iran. Since 2004, Abdul Qadeer Khan has been under a state of house arrest. In an e-mail interview, he now explains why he accepted sole blame for the accusations at the time and points a finger at the Pakistani army.

Spiegel Online: Recent attacks on a naval base in Karachi, Pakistan, which resulted in the deaths of 16 people, show that extremists are posing a serious threat to the government in Islamabad. How safe is the Pakistani nuclear arsenal?

Khan: This hype has been created by the West. There never was, there is not and there never will be any threat to our nuclear assets. Right from the early 1980s on, the army put a fully fail-safe mechanism in place, which was subsequently improved upon by successive army chiefs.