President Trump declared that ISIS is "falling fast" prior to his national security briefing at the Pentagon Thursday.

Trump asserted to reporters prior to the discussions that the US was making notable progress in the fight against the terror group.

"We're doing very well against ISIS," Trump said. "ISIS is falling fast. Very fast."

The two-hour meeting, which aimed to cover "the state of the world," was attended by numerous senior administration officials including Vice President Mike Pence, Secretary of State Rex Tillerson, Chairman of the Join Chiefs General Joseph Dunford and Defense Secretary James Mattis.

The president – who recently gave Mattis the authority to control troop levels in Afghanistan, Iraq, and Syria – did decline however to reveal the White House's intentions on a potential troop increase in Afghanistan.

"You'll be hearing," Trump said.

Mattis is reported to be considering a plan in which an additional 4,000 to 5,000 troops would be sent to Afghanistan where ISIS has grown over the past several years.