The sanctions included three Islamic State-Somalia officials involved in arms trade, financing and other activities.
The Treasury also placed on its blacklist eight individuals and one company involved in the multi-million dollar arms network between Iran, Yemen and the horn of Africa, allegedly feeding the violence by Al-Shabaab and Islamic State in Somalia.
"The individuals and entity designated today are critical nodes for a weapons trafficking network that is closely integrated with ISIS-Somalia," the Treasury said, using its acronym for Islamic State.
"These networks operate primarily between Yemen and Somalia and have strong ties to Al-Qaeda in the Arabian Peninsula (AQAP) and al-Shabaab," it said.
The sanctions freeze any blacklisted person's assets under US jurisdiction and ban US individuals and businesses, including international financial groups with US operations, from doing business with them.
The Treasury described networks partly centered on Puntland on the eastern tip of Somalia, where it said Abdirahman Mohamed Omar has handled more than $2 million in arms deals over the past four years.
"Omar has been involved in weapons facilitation to ISIS-Somalia and al-Shabaab since at least early 2017," working with an Al-Qaeda in the Arabian Peninsula [AQAP] arms facilitator, the Treasury said.
In a mid-2021 deal, it said, Omar acquired a shipment of assault rifles, machine guns, and rocket-propelled grenades and launchers from Iran for Islamic State-Somalia.
The sanctions also hit Brazil-based Osama Abdelmongy Abdalla Bakr, who the Treasury said contacted officials of North Korea in 2016 in an attempt to buy weapons and anti-drone technology for Islamic State-Somalia.
The purchase never took place, the Treasury said.