The State Department designated AQIS a “foreign terrorist organisation” and its leader, Indian-born Asim Umar, a “specially designated global terrorist.”
Al-Qaeda, the jihadist movement founded by the late Osama bin Laden, has long been a banned group, but Thursday’s order singles out a relatively new offshoot.
Bin Laden’s successor, Egyptian Islamist ideologue Ayman al-Zawahiri, announced the formation of AQIS in September 2014 to carry the group’s fight to India, Pakistan and Bangladesh.
Since then, the group has claimed responsibility for a number of deadly and sometimes spectacular attacks, which may explain the US decision to list it separately.
Under the new designation, if investigators tie any assets or property under US jurisdiction to the group or its leader, they will be frozen.
In addition, US citizens are forbidden from having any dealings with the group on pain of prosecution.
In a statement announcing the order, the State Department said AQIS had claimed responsibility for the September 6, 2014 attack on a Pakistani naval dockyard.
The attack left one Pakistani officer and three attackers dead, while seven sailors were wounded as the militants attempted to hijack a docked frigate.
More recently, the group claimed the killings of several Bangladeshi atheists, gay rights activists, bloggers, US citizen Avijit Roy and US embassy employee Xulhaz Mannan.
Umar, who has appeared in Al-Qaeda propaganda as the AQIS leader, is a shadowy figure.