The White House has been presented intelligence estimating that Taliban-led forces battling U.S. and NATO troops in Afghanistan have grown nearly four-fold in the last four years, Reuters quoted officials as saying today. The U.S. intelligence assessment, showing the number of active fighters in the insurgency is now roughly 25,000 from 7,000 in 2006, spotlights Taliban gains and the tough choices facing President Barack Obama in trying to reverse the trend. Obama launched a broad review of his war strategy after the top commander in Afghanistan, General Stanley McChrystal, gave him a grim assessment of the war and an Afghan election, marred by fraud charges, raised U.S. doubts about President Hamid Karzai's legitimacy. At a strategy session on Friday, Obama and his top advisers were expected to discuss McChrystal's request to deploy 40,000 more troops in Afghanistan next year as part of a revised counterinsurgency plan aimed at reversing Taliban gains. Officials said Obama remains undecided about the request. McChrystal's proposed increase -- on top of the 65,000 U.S. troops and 39,000 allied forces currently in Afghanistan -- and the broader strategy review present Obama with what may be the most difficult choice of his young presidency. As U.S. and NATO casualties have soared, public support for the eight-year-old war has eroded. Sending 40,000 more troops, which sources say McChrystal sees as the minimum number needed, could spark a backlash within Obama's own Democratic Party.