According to officials, tow missiles were fired by a U.S. drone into Pakistan's North Waziristan tribal region on the Afghan border on Wednesday, killing at least 21 people.
The victims are suspected militants and all are not Afghan. According to sources, details of the strikes are still emerging. Initial reports said five militants were killed in the attack, but the death toll kept on increasing and new reports suggest that the death toll has now risen to 21 people.
The drone targeted a house located in the east of Miranshah, the main town of the region, known to be a hotspot for Taliban and al-Qaeda insurgency and militants.
"The dead included local Taliban as well as some Arabs and Uzbek nationals," one intelligence official in North Waziristan, speaking on the condition of anonymity, told The Guardian.
Drone strikes have been a major source of friction between the U.S. and Pakistan, and the news is set to create further tensions between the two countries.
The U.S. and Pakistan have maintained they were strong allies, both committed to fighting terrorism.
Since the death al-Qaeda chief Osama bin Laden in a secret U.S. raid in the city of Abbottabad, Pakistan, however, relations seem to have slowly deteriorated.
The Obama administration has been more demanding on Pakistan since then, questioning the authorities' commitment against al-Qaeda.
Pakistan, on the other hand, insisted it was unaware Bin laden was on its territory and described the U.S. raid as a violation of its sovereignty.
Drones have also been a cause of friction between the two countries, as despite Pakistan publicly opposing the strikes, allegations that it had allowed them behind the scenes rapidly surfaced, with sources even hinting that the two countries prepare the strikes together.
Steve Coll, the president and CEO of the New America Foundation, recently said that the Pakistan government "has not only known about them [US drone strikes] but it has also sanctioned and supported them."
"However, there have been debates about the extent of the Pakistani involvement in the program. Throughout the process, the Pakistani authorities have provided logistical support - air bases, permissions- to the United States," Coll, told the Pakistani newspaper Dawn in an exclusive interview.
After the raid however, Pakistani public opinion increasingly turned anti-U.S., and the government was blamed for not being more in charge of what takes place on its own territory, which led the head of the army, General Ashfaq Kayani, to condemn the drone programme and called for its end.
Meanwhile, according to the Conflict Monitoring Center's latest report, the Central Intelligence Agency (CIA) has killed at least 443 people in Pakistan in 51 drone attacks this year so far.
"These six attacks were carried out on three different days of the month, which shows that the month was relatively calm. However, the reduction in number of drone attacks cannot be seen a permanent factor as fluctuation in frequency is seen constantly during the year 2011," the CMC report said.
"The CMC data shows that the CIA's focus is back on North Waziristan, as five out of six drone strikes were recorded in North Waziristan," it added.