WASHINGTON (NYTIMES) - The United States on Thursday (Jan 5) officially listed a son of Osama bin Laden as a "global terrorist," and warned that the younger man, who has called for attacks around the world, poses a risk to US national security.

Hamza bin Laden, 27, who has pledged to take up his father's violent mantle and avenge his death, is "actively engaged in terrorism," the State Department said.

Placing bin Laden on the government list, formally known as the Specially Designated Global Terrorist list, gives officials legal tools to isolate him and hamper his movements and transactions.

It is also a reminder of the continued terrorism campaign by Al-Qaeda, which Osama bin Laden founded, and its affiliates, and of its aim to recruit and groom a new generation of militants.

Hamza bin Laden, one of Osama bin Laden's 23 children, was named a member of the terrorist group in 2014 by his father's successor, Ayman al-Zawahri. Since then, in a series of recorded messages, bin Laden has called for attacks on Western capitals and warned Americans that they would be "targeted in the United States and abroad," the State Department said.

Last year, in a video released by Al-Qaeda's media outlet As-Sahab, bin Laden pledged to avenge his father's death, warning Americans that if they believed the killing of his father by US forces in 2011 had "passed without punishment, then you thought wrong."

From a young age, bin Laden expressed an interest in joining his father's terrorist campaign. As a boy, he appeared in propaganda films, and documents found after his father's death indicate that the young man was being groomed for an Al-Qaeda leadership role.

In 2009, in a letter discovered at his father's hideout in Pakistan and eventually reported by US officials, bin Laden wrote: "My beloved father, I was separated from you when I was a small child, not yet 13, but I am older now, and have attained manhood."

"But what truly makes me sad," he added, "is the mujahedeen legions have marched and I have not joined them."

A letter said to have been written by Osama bin Laden in 2010 called his son "very sweet and good" and described his ardor to join Al-Qaeda's fight.

"He comes back to me asking me that he should be trained and participated in giving," the letter read. "He does not want to be treated with favouritism because he is the son of 'someone.' I promised him to plan some safe training for him: firing arms and with various weapons."

The young man is one of the few children of Osama bin Laden who openly expressed a willingness to follow in his father's footsteps.

The US government incorrectly said he was among the dead in the US raid that killed his father, later issuing a correction to say that another son, Khalid, had been killed and that Hamza had not been in the home at the time.

His mother is Khairiah Sabar, a native of Saudi Arabia who was among those captured in the raid in Abbottabad, Pakistan. She was later released.