President Donald Trump

US President Donald Trump has delegated the authority to set official troop levels in the fight against ISIS in Iraq and Syria to Secretary of Defense James Mattis, the Pentagon said Wednesday.
"At the request of Secretary of Defense Mattis, the president has delegated force management authority to the secretary," Pentagon spokesman Maj. Adrian Rankine-Galloway told the (CNN).
He said the change "enables military commanders to become more agile, adaptive and efficient in supporting our partners." Under the Obama administration, troop levels were set by the White House. 

Source: QNA