Obama believes Assad must be removed to defeat Islamic State

President Obama has realized that the Islamic State of Iraq and Syria cannot be defeated unless Syrian dictator Bashar Assad is removed from power, CNN reported Wednesday.

The president has reportedly requested his national security team revisit the U.S. policy toward Syria in light of this change. The White House has held four meetings of the team in the past week, CNN said. Obama chaired one of those meetings.

Multiple sources told CNN that Obama recognizes the folly in attempting to decisively defeat the Islamic State in Iraq before turning to Syria.

"Developments on the ground have caused the national security team to collectively conclude we may not have time for Iraq first. In an ideal world you would drive [Islamic State] out of Iraq and pivot to Syria. But if by then the moderate opposition has been smacked and [the Islamic State] is still there, that doesn't help," a source told CNN.

Options reportedly include a no-fly zone over the Turkey-Syria border and speeding up troop training.

U.S. military officials have warned that it may take a year to train Syrian rebels.