The head of U.S. Central Command in Afghanistan warned that months of fighting lie ahead in what will likely be the biggest military operation there since the American-led invasion of 2001, AP reported.
Gen. David Petraeus said the effort will center on 10 percent of districts where about 70 percent of Afghanistan's violence occurs.
Petraeus was in San Francisco as part of a national speaking tour - he gave a talk in Seattle on Wednesday night. He was greeted warmly at the Marines' Memorial Club by a mostly male, pro-military crowd that included many veterans.
During his hourlong speech, which included a PowerPoint presentation, Petraeus warned of a tough fight as Marines have recently gone deeper into Taliban areas of southern Afghanistan to "reverse the cycle of violence" there.
He described it as, "the longest campaign."
Petraeus added that it will take a "sustained and substantial commitment" to prevent the Taliban from making the area a hot spot for terrorists. He said it's especially important for troops to have a presence prior to presidential elections there next month.
He said about 68,000 American troops will be in Afghanistan by this fall - more than double the number from last year. He also mentioned armored Stryker vehicles, which were successful in Iraq, will be in Afghanistan and likely deployed in the troubled Kandahar province.
Petraeus, 56, is best known for coordinating the troop surge in Iraq that is credited with significantly reducing the country's violence. He said while Iraq has made significant progress, it's also in a significant period of transition and fragile situation.
"The fabric of the society has perhaps had a stitch or two put back into it as the security has improved," Petraeus said. "But I don't want to overstate that at all."
During the talk, about 50 people demonstrated outside calling Petraeus a "war criminal." Police said no arrests were made.