"In my mind, ISIS is a 10- to 20-year problem, it's not a two-years problem," said General Ray Odierno, the Army chief of staff, using an alternative acronym for the group. "Now, I don't know what level it will be a problem, but it's a long-term problem."
The White House has cautioned that the fight against IS could last years. Odierno's assessment is an expansion of the timelines offered by the Obama administration, and is by far the longest timetable laid out by a Pentagon official, Reuters reported.
"The administration has said 'three to five' years. I think in order to defeat ISIL, it's going to take longer than that," Odierno said. "This movement is growing right now, and so I think it's going to take us a bit longer than we originally thought."
He added that a solution to the militant group cannot come by purely military means, but must be multi-faceted.
"To defeat them is not just a military issue. It is an economic issue. It is a diplomatic issue. It is an issue of moderate versus extremists and it is about also, potentially, having the capability to root them out of the places they now hold in Iraq and Syria."
Odierno, who is retiring in August, said that due to budget cuts, the Army is "not going to be able to do everything we’re being asked to do."
The general echoed the Obama administration's goal of having the fight against IS militants be handled primarily by local forces on the ground, according to Reuters.
"Others should do this," he said. "I believe the nations in the Middle East need to solve this problem. We should be helping them to solve this problem."