The number of missiles fired into North Waziristan was unusually high, reflecting multiple targets.
They struck cars, homes and tents across a wide area in the Doga area, where insurgents have hideouts and training facilities, two intelligence officials said on condition of anonymity because they were not authorized to speak to the media. The identities of the people killed in the attack were not immediately known.
North Waziristan has been the target of nearly all of about 30 other American attacks this year. In recent months, it has become a new haven for militants who fled a Pakistani army offensive in their previous stronghold, neighboring South Waziristan.
The strike Tuesday was the third since Pakistani-American Faisal Shazad was arrested after allegedly abandoning a bomb-laden SUV in Times Square. He has reportedly told investigators that he received training in Waziristan and U.S. officials have said evidence showed the Pakistani Taliban played a role in the plot, though Pakistani officials.
Since his arrest,, going a week without appearing in court on weapons of mass destruction and terror charges. Federal authorities say 30-year-old Shahzad voluntarily waived his right to an initial court appearance and agreed to answer questions, possibly without a lawyer and while in custody at an undisclosed location.
Pakistan officially protests the missile strikes on its territory as violations of its sovereignty, but it is believed to aid them. The U.S. rarely discusses the unmanned-drone-fired strikes, which are part of a covert CIA program.
that the Pakistani Taliban were behind the May 1 failed car bombing in Times Square add pressure on Pakistan's government to launch an army attack on the militant sanctuaries of North Waziristan, but few expect its stretched army to rush into any operation there.
New calls from Washington could backfire because they would create the impression the force was acting on the orders of America - a perception that would undercut the public support needed for such an operation to be successful.
Aside from U.S. Secretary of State Hillary Rodham Clinton's warning over the weekend of "severe consequences" if an attack on U.S. soil is traced back to Pakistan, most U.S. officials have been careful not to criticize Pakistan in their public comments since Pakistan-American Faisal Shahzad was arrested soon after the terror attempt in New York.
America is limited in what it can do to tackle the threat coming from Pakistan's tribal regions.
It is seen as highly unlikely that nuclear-armed Pakistan would ever allow American troops to operate there, meaning Washington must try to work through the Pakistani army, which has received billions of dollars in U.S. aid since 2001.
The Pakistani Taliban, which have previously not conducted attacks on U.S. soil, have been the target of several Pakistani army offensives over the last two years in addition to being battered by scores of American missile strikes. They are allied to al Qaeda, which has also found sanctuary in the northwest, and the Afghan Taliban just across the border.
The army has not moved into North Waziristan in part because powerful insurgent commanders there have generally not attacked targets in Pakistan. In recent months, however, fleeing fighters and commanders from the Pakistani Taliban - which have launched scores of bloody suicide attacks around the country since 2007 - have moved there.