Osama bin Laden's son Hamza wants to avenge his father's death, an ex-FBI agent has claimed.
The claims were made in an episode of CBS News' 60 Minutes TV program, in which former-FBI agent, Ali Soufan, examined letters found at Osama's compound after he was killed in 2011.
Soufan was the lead investigator into al Qaeda following the 9/11 attacks.
The personal letters, which have now been declassified, reveal Hamza's desire for revenge following the death of his father.
Soufan said: "He's basically saying, "American people, we're coming and you're going to feel it. And we're going to take revenge for what you did to my father...Iraq...Afghanistan"...the whole thing was about vengeance."
One of the letters is said to have read: "Every look... every smile you gave me, every word you told me, I consider myself to be forged in steel.
"The path of jihad for the sake of God is what we live [for]."
At the time of his father's death Hamza was 22 and was tipped by security experts as the next head of al Qaeda. He appeared in a number of propaganda as a child, often holding a gun.
Soufan said: "He was a poster kid for al-Qaeda... and for members of al-Qaida, who were indoctrinated with these propaganda videos, he means a lot to them."
The letters are part of a larger collection of documents found at the compound, which have now been released to the public. As well as letters to and from family members, there are also a number written by senior members of the al Qaeda terrorist group.
Back in 2015 al Qaeda released an audio message of Hamza, in which he called for terrorist attacks in the west. He is also reported to have threatened terrorist attacks in London and Paris, as well as the US.
He was placed on the US state department terrorist watch list in January.