Pakistan said the P3C aircraft, modified with the latest avionics, are designed to improve surveillance in the North Arabian sea, one of the world's most important shipping routes deeply troubled by Somali piracy.
"The two aircraft have been delivered to the Pakistan navy. These aircraft have been provided under the foreign military funding programme," a spokesman for the US embassy in Islamabad, told AFP.
Relations between Pakistan and the United States were severely damaged last year by a covert American raid that killed Osama bin Laden and air strikes that killed 24 Pakistani soldiers, and the alliance remains tense.
The navy said the aircraft would help "maintain requisite vigil in our vital area of interest in the North Arabian Sea", which it said was "home to intense maritime activity both legal and illegal and thus warrants continuous guard".
Pakistan is to receive six P3C aircraft from the United States in three batches. The first two, received in 2010, were destroyed during a 17-hour siege of a key naval base in Karachi last May blamed on the Taliban.
The attack killed 10 personnel and deeply embarrassed the military, just three weeks after bin Laden was killed in the garrison town of Abbottabad.
Times of India