Husayn Juaythini maintains ties with Islamic State in Iraq and the Levant (ISIL), listed as Al-Qaida in Iraq (QDe.115). As of January 2015, Juaythini was instrumental in fostering connections between Gaza and Libya-based terrorists and facilitating their travel to the Syrian Arab Republic. In 2014, Juaythini was working to assist fighters moving to the Syrian Arab Republic.
As of September 2014, Juaythini had traveled to the Syrian Arab Republic to pledge allegiance to ISIL and was tasked by ISIL leadership to return to Gaza to establish an ISIL foothold. Juaythini was the link between ISIL leader Abu Bakr al-Baghdadi, listed as Ibrahim Awwad Ibrahim Ali al-Badri al-Samarrai (QDi.299), and armed groups in Gaza and was using money to build an ISIL presence in Gaza.