Strengthening Security in the Indo-Asia-Pacific Act This bill requires the Department of Defense (DOD) to report to Congress regarding: U.S. defense priorities and challenges emanating from the Indo-Asia-Pacific region, including challenges from North Korea and China; an assessment of the U.S. force posture and basing needs in such region; an assessment of the actions and resources necessary to retain an eleventh combat aviation brigade in South Korea; an assessment of the Air Force's ability to employ bombers and associated weapons while forward deployed in support of operations in such region; a plan for enhancing the sharing of commercial imagery and national technical means with South Korea and Japan; a plan for identifying areas of cyber security collaboration and partnership with Asian allies and enhancing information operations and strategic communication strategies to counter Chinese, North Korean, and Russian information warfare and propaganda activities; and an assessment of Freedom of Navigation Operation patrols in the South China Sea. FY2018 funds are authorized for DOD: (1) to address critical munitions shortfalls; (2) to procure area or missile defense interceptors; (3) for armed forces exercises with Japan, South Korea, and Australia; and (4) for joint training through the Combatant Commanders Exercise Engagement and Training Transformation Program.