The Pentagon sharply raised its estimate of the number of US troops currently in Afghanistan Wednesday, ahead of a decision on adding thousands more under President Donald Trump's new strategy for the war-ridden country.

Pentagon Joint Staff Director Lieutenant General Kenneth McKenzie said a comprehensive review showed there were approximately 11,000 uniformed US servicemen and women in Afghanistan, compared to the 8,400 number used since last year.

The new count, which includes temporary and covert units as well as regular forces, was made to establish the basis for an increase in troops -- possibly by around 4,000 -- under Trump's revised strategy to better support Afghan troops in the fight against the Taliban.