One of the sons of Osama Bin laden, 23-year-old Hamza, is calling for terrorist attacks to avenge his father’s death, according to an audio released by al-Qaida’s media arm.

In the audio message posted online, The Crown Prince of Terror has threatened revenge against the United States for assassinating his father, the slain al Qaeda leader Osama bin Laden, and promises to continue the global militant group’s fight against the United States and its allies in the 21-minute speech entitled “We Are All Osama,” according to the SITE Intelligence Group.

Hamza’s whereabouts are unknown and is thought to have been groomed by his 9/11 mastermind father.

This is not the first time that Hamza calls for terrorist attacks. Previously, he hashad incited attacks on on London, Washington, Paris and Tel Aviv in an audio message released by al-Qaida.

Hamza says al-Qaida will continue waging jihad, or holy war, against the US in response to its ‘oppression’ of Muslims.

‘If you think that your sinful crime that you committed in Abbottabad has passed without punishment, then you thought wrong,’ he says, referring to his father’s May 2011 death during a US raid at his compound in Afghanistan.

“We will continue striking you and targeting you in your country and abroad in response to your oppression of the people of Palestine, Afghanistan, Syria, Iraq, Yemen, Somalia and the rest of the Muslim lands that did not survive your oppression,” Hamza said.

“As for the revenge by the Islamic nation for Sheikh Osama, may Allah have mercy on him, it is not revenge for Osama the person but it is revenge for those who defended Islam.”

Osama bin Laden was killed at his Pakistani hideout by U.S. commandos in 2011 in a major blow to the militant group which carried out the Sept. 11, 2001 attacks.

Documents recovered from bin Laden’s compound and published by the United States last year alleged that his aides tried to reunite the militant leader with Hamza, who had been held under house arrest in Iran.

Hamza, now in his mid-twenties, was at his father’s side in Afghanistan before the 9/11 attacks and spent time with him in Pakistan after the U.S.-led invasion pushed much of al Qaeda’s senior leadership there, according to the Brookings Institution.

Introduced by the organization’s new chief Ayman al-Zawahiri in an audio message last year, Hamza provides a younger voice for the group whose aging leaders have struggled to inspire militants around the world galvanized by Islamic State.