Although the U.S. knows "almost nothing" about the new leader of ISIS, he is "a nobody," according to a senior State Department official, making it difficult for the terror group to rally around him. 

Amid the hunt for the new ISIS leader, the U.S. will leave between 700 and 900 troops in Syria, with the official saying the "goals and means" of defeating ISIS, ridding Syria of Iranian-commanded forces, and securing a political transition haven't changed, despite President Donald Trump's new focus on "taking" oil. 

Trump said last Friday that he and his administration "know exactly who [the new leader] is!" one day after the terror group announced a new leader under the nom de guerre Abu Ibrahim al-Hashimi al-Qurashi. Al-Hashimi replaces Abu Bakr al-Baghdadi, the terror chief that created the group, expanded it to the so-called "caliphate" the size of Great Britain, and killed himself in an explosion amid a U.S. special forces raid in late October.

Read more: ABC News