Washington (AFP) - The Islamic State group is falling "very fast," US President Donald Trump said Thursday as he visited the Pentagon for a military strategy meeting.

US President Donald Trump (C) shakes hands with US Defense Secretary James Mattis (L) as he arrives at the Pentagon in Washington for a strategy session on defeating IS © AFP JIM WATSON Washington (AFP) - The Islamic State group is falling "very fast," US President Donald Trump said Thursday as he visited the Pentagon for a military strategy meeting.

"We're doing very well against ISIS. ISIS is falling fast, very fast," Trump said, using another acronym for IS.

Trump's comments come at the six-month mark of his presidency, for which he campaigned by vowing to quickly defeat IS.

While the strategy to beat the jihadists in Iraq and Syria follows largely that of the Obama administration, Trump has given battlefield commanders more power to call in strikes and make real-time decisions.

IS has suffered a string of setbacks over the past two years, including the loss of their Iraq bastion Mosul earlier this month.

The intense destruction of the city and ongoing operations to retake Raqa in Syria have led critics to say the Trump administration is paying less attention to protecting civilians.

Trump signed an executive order soon after taking office giving his generals 30 days to come up with a revised plan to wipe the jihadists out.

The review resulted in an "annihilation campaign" against IS, but details are still being discussed and it has been broadened into a wider regional strategy.

Trump's brief comments actually came after he was asked whether he would be sending troops to Afghanistan, where the US has been since late 2001.

"We'll see," he said.

Pentagon officials have said Defense Secretary Jim Mattis is considering adding around 4,000 troops to augment the current "train and advise" mission for local forces.

Also attending Thursday's meeting at the Pentagon were Secretary of State Rex Tillerson, Treasury Secretary Steven Mnuchin and General Joe Dunford, chairman of the Joint Chiefs of Staff.