Internal Security Service (ISS; Arabic: جهاز الأمن الداخلي, transliterated: Jahaz al Amn al Dakhly) is the national security agency of the Sultanate of Oman.

[2] The stated overall purpose of ISS is to investigates all matters related to internal security.

[3][4][5] The ISS also leads on Omani counter terrorism procedures and outreach activities.

[12][13] In 1994 and 2005 there were attempted coups against the Sultan's rule and the ISS would have been instrumental in uncovering and investigating the plots.

[19] Lieutenant General Said al Hilali's brother is the Sultanate's Public Prosecutor, who was reported in 2012 to be ready to use the law to restrict freedom of speech and association.