From the Budget Summary: "The United States Government's strategy to counter the Islamic State of Iraq and Syria (ISIS) directed the U.S. Department of Defense (DoD) to degrade, dismantle, and ultimately defeat ISIS using two primary lines of effort: denial of ISIS safe havens and building partner capacity. The Counter-ISIS Train and Equip Fund (CTEF) is a crucial part of the United States' whole-of-government approach to support the lasting defeat of ISIS. The CTEF specifically supports the DoD's efforts to work 'by, with, and through' the Iraqi Security Forces (ISF) and the Vetted Syrian Opposition (VSO) to build key defeat-ISIS capabilities and promote the long term stability of the region by preventing the resurgence of ISIS. [...] The details that follow in this budget justification book represent the Department's best assessment of areas where CTEF support is will be needed in the future, and a best estimate of associated funding. Because of the dynamic nature of the counter-ISIS fight, the changing requirements on the ground, and the timelines involved, DoD will notify details of obligations to the congressional defense committees, as required by the CTEF appropriation."