The "No Equipment Left Behind Act of 2026" addresses concerns about United States-origin defense equipment being captured or diverted by hostile actors following U.S. military withdrawals or force reposturing. Congressional findings highlight instances such as equipment falling to ISIL in Iraq in 2014 and the Taliban in Afghanistan in 2021, underscoring significant financial losses and security risks. The bill emphasizes the need for comprehensive equipment accountability, cost transparency, and partner force resiliency assessments to mitigate such diversions. To achieve this, the bill amends title 10, United States Code, by requiring the Secretary of Defense to submit detailed reports to congressional defense committees within 60 days of initiating any significant force reposturing or withdrawal from a covered theater of operations. These reports must include a comprehensive inventory of accountable property, assessments of potential dispositions (such as retrograde, destruction, or sale), and estimated incremental costs for each option. Crucially, the reports must also outline a plan to mitigate the risk of diversion or misuse, including end-use monitoring, remote disablement capabilities, and procedures for sensitive technology. Furthermore, the legislation mandates senior approval by the Secretary or Deputy Secretary of Defense for certain dispositions exceeding $10,000,000 in aggregate replacement value, such as abandonment or destruction. It also requires annual reports summarizing property dispositions, incidents of equipment diversion, and implemented risk mitigation measures. The Secretary must provide prompt notifications to Congress if an ally or partner force collapses or if diverted U.S. property is used in an attack by a foreign terrorist organization, ensuring greater transparency and accountability for military assets abroad.