The Haqqani Network has close ties to Al-Qaeda and has been blamed for many of the most deadly attacks against US and government targets in Afghanistan.
The group´s leader Sirajuddin Haqqani has long been one of Washington´s most important targets, and is now joined by his brother Abdul Aziz Haqqani on the blacklist.
Sirajuddin was last month named as one of two deputy leaders of the Afghan Taliban.
“For several years, Aziz Haqqani has been involved in planning and carrying out improvised explosive device attacks against Afghan government targets,” the State Department said.
According to the statement, Aziz Haqqani also “assumed responsibility for all major Haqqani Network attacks after the death of his brother, Badruddin Haqqani.”
Aziz already had a $5 million US bounty on his head and the Haqqani faction has long been designated a “terrorist organization.”
He now joins his brother as subject to the seizure of any assets he may have in areas under US control, while Americans are banned from doing business with him.
With Abdul Aziz, the family network is led by Sirajuddin´s uncle and brother-in-law along with Abdul Rauf Zakir, the alleged head of the group´s suicide operations.
The Haqqani Network was set up in the 1970s as a force to oppose the Marxist regime in Kabul and its Soviet backers, and fought in the Afghan civil war.
US intelligence holds it responsible for some of the most audacious strikes of the insurgency, including the 2009 Camp Chapman bombing, which killed seven CIA agents.