What is Sikhs for Justice, banned Khalistani group that allegedly gave $16 mn to AAP?

Khalistani leader Gurpatwant Singh Pannun's Sikhs for Justice (SFJ) is a New York-based organisation that is banned in India. Arvind Kejriwal's AAP has been accused of receiving $16 million (around ₹133 crore) from SFJ. The organisation claims to be aimed at establishing "sovereign state of Khalistan" and has been accused by NIA of 'radicalising Indian youth into undertaking terror activities'.