Yahya Farooq Mohammad, Ibrahim Zubair Mohammad, Asif Ahmed Salim and Sultane Room Salim were charged with supporting violent jihad against US military personnel in Iraq, Afghanistan and throughout the world.
Al-Awlaki, a key leader of al-Qaida in the Arabian Peninsula, was designated a global terrorist in 2010 and killed by a US drone airstrike in Yemen in 2011.
There is a global crackdown on militant supporters who raise funds to help the terrorists carry out militant activities.
The US has in the recent past have heaved sanctions against terrorist financiers in a bid to incapacitate terrorist activities. Most prominent was the August 2015 US sanctions on two Qatari men, Saad bin Saad Mohammed Sharyan al-Kaabi and Abdul Latif Bin Abdallah Salih Muhammad al-Kawari who were involved in financial support for al-Qaeda and its Syrian affiliate, Al-Nusra Front.
Al-Kaabi and al-Kuwari ran large networks of funding and that sanction against the Qatari men has had a significant impact on their ability to raise any further funds in the region.
The US treasury has previously blamed Qatar of creating a tolerant atmosphere that allows the raising of funds and support of extremist organizations, especially those operating in Syria.
Qatar is still believed to be the political headquarters for Hamas and its leader, Khaled Meshal, and it has declined to punish private financiers of terrorist groups such as al-Qaeda.