The issue focused on the "dramatic" rise of the Islamic State in Iraq and the Levant (ISIL).

A former senior US intelligence official said that the threat level was "substantially higher" for ISIL than it was for al Qaeda or Boko Haram, which are "a much greater threat."

"The danger level remains elevated for ISIL, but in a less extreme form," the senior US official said.

The official spoke on condition of anonymity to describe sensitive discussions on an