Missile-firing U.S. drone aircraft killed at least 16 people on Friday in an attack in northwest Pakistan, Reuters cited two Pakistani intelligence officials as saying. The attacks targeted three walled compounds in the Shawal Valley, which is in the South Waziristan region on the border with Afghanistan, the officials said. The area has long been known as a sanctuary for militants. The drone attacks are highly controversial in Pakistan, where there is anger over civilian casualties and what is perceived as a violation of Pakistani sovereignty. But U.S. officials say that Pakistan does not control the militant-held territory where the drones strike. The United States considers drones a key weapon in the war against al Qaida and Taliban insurgents. -- SPA