World Bulletin / News Desk

The rise of ISIL in Iraq and Syria caught President Barack Obama and his intelligence officers by surprise, he acknowledged during remarks aired Wednesday.

"The ability of ISIL to not just mass inside of Syria, but then to initiate major land offensives that took Mosul, for example, that was not on my intelligence radar screen," he told CNN, referring to the Islamic State of Iraq and the Levant, another name for ISIL.

The terror group stormed Iraq's second largest city in June 2014. The Iraqi government and allied forces are engaged in an ongoing campaign to wrest control of Mosul from the terror group, but the fighting has been intense and successes in city have been slow to accumulate.

Obama famously called the group the "jayvee" team of terror early on as it spread through Iraq, a comment now met with derision from critics.

ISIL's rise has been one of the central foreign policy and security challenges Obama has sought to combat in a tumultuous region. And its affiliates have since spread to North Africa.

Obama maintained that avoiding a large-scale invasion in Syria is nonetheless "the smartest decision from a menu of bad options that were available to us”.

While a small number of U.S. special forces have carried out raids against the group, Obama has preferred to partner with and train local forces, and prosecute the campaign by air in Iraq and Syria.