The change of name was outlined in a February 13 memo issued by the office of Defense Secretary James Mattis, AP reported. According to the Pentagon chief, the switch to “ISIS” would make the DoD language “consistent with’” that used by the Trump administration in a January 28 directive ordering the department to come up with a new plan to defeat Islamic State (IS).
The group currently known as IS used to call itself Islamic State of Iraq. In 2013, its leader Abu Bakr al-Baghdadi changed the name to “Islamic State of Iraq and al-Sham”, marking its growing ambition.
Al-Sham is an archaic term for a territory that includes parts of Syria, Lebanon, Israel, the Palestinian territories and Jordan. It’s usually translated into English as either “Syria” in the sense of greater Syria of the past or as the Levant, a term close to the territory encompassed by the Arabic Al-Sham.
The group’s name was most commonly translates as the Islamic State of Iraq and Syria (ISIS) or the Islamic State of Iraq and the Levant (ISIL). The administration of President Barack Obama preferred the latter variant.
After capturing large parts of Syria and Iraq in 2014 and becoming a major terrorist threat, the group shortened its name to just Islamic State, corresponding to its claim to build a single caliphate for all Muslims.
In Arab-speaking nations and some other countries like France, the preferred term for IS is Daesh, an Arabic acronym corresponding to ISIS. The word has a somewhat mocking connotation in Arabic.