President Barack Obama says the United States military and allied forces are hitting the Islamic State in Iraq and Syria (ISIS) group harder than ever.

Obama said the group's leaders cannot hide, and the group is losing territory. Obama also said the U.S. strategy of hunting down leaders, training forces and stopping the group's financing and propaganda is progressing.

Obama said ISIS has lost about 40 per cent of the area it once controlled in Iraq, and that the group has been pushed back from much of the territory it held in Syria near the border with Turkey.

The president made the remarks after meeting with his national security team at the Pentagon on Monday. The rare meeting outside the White House is part of a public relations drive to ease Americans' worries about domestic terrorism ahead of the holidays.

Obama is making the case for his broad counterterrorism strategy, including his ongoing campaign against the Islamic State group in Iraq and Syria.

He said Defence Secretary Ash Carter will go to the Middle East to secure more military contributions for the fight against ISIS.

"We recognize that progress needs to come faster," Obama said.

with files from Reuters