Usama bin Laden, seen here in 1998, is the father of Saad bin Laden, believed to be killed in U.S. airstrike.
U.S. officials believe Usama bin Laden's son, Saad bin Laden, was killed in a U.S. airstrike in Pakistan.
Sources confirmed to FOX News late Wednesday that officials believe the younger bin Laden was killed by hellfire missiles from a U.S. Predator drone strike earlier this year.
The death was first reported by National Public Radio.
National Intelligence Director Mike McConnell told NPR that Saad bin Laden reportedly traveled to Pakistan last year after spending several years under house arrest in Iran.
It is believed Saad, who is not considered a significant player in Al Qaeda leadership, was "collateral" damage in the airstrike and was not considered important enough to target on his own.
It isn't possible to tell for certain whether he was killed, since a body has not been recovered, preventing DNA tests, a senior U.S. counterterrorism official told NPR.
The source estimated the chance Saad bin Laden is dead at "80 to 85 percent."
At least 11 senior Al Qaeda operatives have been taken out in the secretive drone campaign which has continued at the same tempo under the Obama administration.
A U.S. official points out that Saad "had a marquee name" but was not actively considered a successor to his father.
"We make a big deal out of him because of his last name," NPR quoted a source as saying.
U.S. forces have stepped up their drone attacks in Pakistan since last September, targeting Taliban and Al Qaeda-linked militants in areas bordering Afghanistan.
The United States has carried out close to 50 such air strikes since the beginning of last year, killing about 470 people, including many foreign militants, according to a tally of reports from Pakistani intelligence agents, district government officials and residents.
FOX News' Catherine Herridge contributed to this report.