Government Accountability Office (GAO) was asked to review Unmanned aircraft systems (UAS) performance in recent joint operations and the soundness of the Department of Defense's (DOD) approach to evaluating joint UAS operational performance. GAO has previously found that DOD's approach to developing and fielding UAS risked interoperability problems which could undermine joint operations. The GAO recommends the Secretary of Defense develop and apply appropriate joint operating standards, and include specific performance indicators and baselines for analysis and systematic information reporting and analysis procedures in the new performance measurement system under development