A pilotless U.S. drone aircraft fired missiles into Pakistan's North Waziristan, an al Qaeda and Taliban sanctuary on the Afghan border, killing at least 12 militants on Saturday, intelligence officials said. The United States has intensified missile strikes by drone aircraft in Pakistan's lawless Pashtun tribal lands in an effort to curb violence in Afghanistan, much of which U.S. officials say comes from militant sanctuaries on the Pakistani side. Most of the missile attacks this year were carried out on militant targets in North Waziristan region. In the latest strike, the missiles hit a house used by militants as a...