Patriot is a mobile Army surface-to-air missile system designed to counter tactical ballistic missiles; cruise missiles; and other threats such as airplanes, helicopters, and unmanned aerial vehicles. Patriot was first deployed in the early 1980s and since that time has received a number of substantial updates to keep pace with the growing threat. Patriot is deployed worldwide in defense of the United States and its allies’ key national interests, ground forces, and critical assets. A Patriot fire unit is made up of four basic components: (1) a ground- based radar to detect and track targets; (2) launchers; (3) interceptor missiles; and (4) a command, control, and communication station. Patriot fire units are organized to fight in groups known as battalions. Each battalion is controlled by its own command and control station and can manage up to six fire units, although a battalion is typically deployed with four. For a notional configuration of a Patriot battalion, see figure 1. Several battalions can be commanded by an Army brigade. Brigades are also responsible for certifying that the equipment can be employed as required and for training the battalions. The brigade manages battalion personnel under its command, with the ability to transfer personnel among battalions to fill personnel gaps as needed. The air and missile defense architecture consists of several systems deployed together to provide a layered defense against various threats in a range of battlespaces. Other air and missile defense systems can contain, like Patriot, a sensor, a launcher, and a system-centric command and control station. These systems’ command and control stations can share information with other air and missile defense systems or with other joint systems through external communication links, as seen in figure 1. The air and missile defense architecture includes systems designed to counter threats at a low altitude—such as rockets, artillery, and mortar— as well as systems designed to defeat high-altitude threats intercepted above the earth’s atmosphere. Patriot serves as the Army’s primary element deployed to intercept targets in this middle range of battlespace—above the range of rockets, artillery, and mortar, but within the earth’s atmosphere. The Army has identified a number of air and missile defense communication and performance capability gaps in its ability to address evolving global threats. Over the last decade, adversaries have acquired more robust, diverse, and complex threats. According to a 2010 Ballistic Missile Defense Review Report, ballistic missiles are more technically sophisticated, more proliferated, include more advanced countermeasures, and continue to challenge U.S. ballistic missile defense system capabilities. Cruise missiles have also become relatively simple to develop, are cheaper than ballistic missiles or aircraft, and are easy to export. Additionally, advanced electronic attacks, such as jamming or spoofing, have become more widespread and easier to effectively produce. Sophisticated enemies also have the ability to use a combination of integrated attacks including electronic and cyber warfare, a variety of inbound ballistic and cruise missiles, special operation forces, and other methods to complicate the battlespace. The Army has identified some high-priority air and missile defense gaps in its ability to respond to the growing threats, as seen in table 1. The Army announced an Air and Missile Defense Strategy in 2012 to address communication and performance capability gaps by integrating its current air and missile defense system components (e.g. sensors and launchers), including Patriot, under a central network and command and control system and linking them with joint and potential coalition allies. The Integrated Air and Missile Defense (IAMD) program is currently developing the IAMD Battle Command System (IBCS) that plans to connect Patriot radars and launchers into IBCS’s central network and command and control stations. By connecting these components directly with IBCS, the Army intends to divest air and missile defense systems of their system-specific command and control stations and allow them to become network enabled sensors and launchers. See figure 2 below for a notional representation of the future Integrated Air and Missile Defense architecture. The Army intends for the integrated air and missile defense architecture to address communication and performance capability gaps by allowing IBCS to collect information from a variety of sensors, fuse that data into a single battlespace picture, and use that information to engage targets. Receiving sensor data from a range of sensors could enable longer- distance engagements and provide commanders with more decision time to select the appropriate response, prevent fratricide, and allow any joint sensor to pair with the best available launcher. In addition, by integrating several individual sensors’ data, IBCS could compare and resolve conflicts within the individual systems’ abilities to accurately classify, identify, and discriminate potential threat objects to provide more accurate data back to the systems. IBCS could also help mitigate the risk of electronic attack since additional sensor data could help confirm where targets are when individual radars are being jammed or spoofed. In addition, because launchers would have access to additional sensor data, they could see more of the battlespace and use that information to more effectively engage threats. IBCS is intended to multiply the performance capabilities of the individual sensors and launchers connected to its network. Therefore, the capability of the networked architecture relies upon the ability of Patriot, as well as other air and missile defense systems, to connect with IBCS and provide the needed quality data for enhanced performance capabilities. Similar endeavors to create a system-of-systems architecture with an extensive communication and information network have proved challenging for DOD in the past. For example, prior work on the Army’s Future Combat Systems, a multibillion dollar development program originally consisting of 18 manned and unmanned systems tied together by an extensive communications and information network, faced rising costs and technical challenges that eventually led to its cancellation. In 2014, DOD provided guidance to the Army for conducting its LTAMD analysis of alternatives (AOA) to explore options for an efficient and cost- effective long-term radar and launcher solution—with considered alternatives ranging from the current Patriot assets with modifications up to total replacements—that will be able to connect with IBCS and address capability needs related to radar reliability, range, and 360-degree surveillance. The AOA results will support a decision for a new radar acquisition program, known as the LTAMD sensor, that will require a significant long-term financial investment. Issues with the Patriot radar have been raised in the past. For example, the Director of Operational Test and Evaluation identified performance and reliability issues with the current Patriot radar in its annual report since 2013. In addition, the Army conducted a business case analysis in 2013 and found that upgrades to the Patriot radar could result in operations and support savings, performance improvements, and reliability enhancements. An AOA is a key first step in the acquisition process, intended to assess alternative solutions for addressing a validated need. AOAs are generally performed or updated to support key acquisition decision points. During the course of our audit, an official in the Office of the Secretary of Defense for Cost Assessment and Program Evaluation (CAPE) stated that he expected the final LTAMD AOA report to receive approval in the third quarter of fiscal year 2016. As of August 2016, the report was still under independent review with the CAPE. To prepare the warfighter for the transition from the current, or legacy, Patriot system to IBCS-integrated Patriot radars and launchers, the Patriot program identified a need for training upgrades. Upgraded training aids and devices are necessary because transitioning to IBCS changes the way the warfighter employs the Patriot equipment. The Patriot program has also identified a need to continue substantial investments to address obsolescence and sustainment issues. For example, the process of upgrading all of the legacy Patriot battalions to IBCS-integrated radars and launchers is an 8-year process that officials expect to begin in fiscal year 2017 and complete in fiscal year 2025. The legacy Patriot system components need ongoing obsolescence and sustainment improvements to improve reliability and availability, remain affordable, and be compatible with the different versions of operational Patriot battalions during that time. In addition, the program intends to continue obsolescence and sustainment investments to maintain readiness, improve reliability, and lower sustainment costs to support deployed forces with legacy radars until the legacy radar is fully replaced. Officials estimate that a new radar development could begin fielding in the fiscal year 2028 time frame with tactical fielding completing within 7 years. However, these plans are still preliminary and the milestone approval process is still underway. Lastly, obsolescence and sustainment improvements support legacy versions of Patriot systems, which foreign military partners continue to buy and operate. Patriots have been sold world-wide to 12 foreign military partners who share costs for sustainment and capability improvements in addition to investing in development to mitigate system obsolescence. The currently fielded version of Patriot represents an improvement over prior versions through upgraded software, a more capable missile, and increased processor capabilities. However, the current version demonstrated a number of performance shortfalls against its documented requirements. In addition, warfighters from various combatant commands have expressed critical needs for additional performance capabilities and training equipment for the Patriot system that are currently unmet. The current version of the Patriot system added performance capabilities through a software and processor upgrade in 2013 and an upgraded missile and launcher that began fielding in fiscal year 2016. In 2013, the Patriot program released its current system software upgrade known as Post Deployment Build-7 (PDB-7) that provided improvements in threat tracking, debris mitigation, and user interface. The software is supported by a new modern processor in the command and control station. This new processor provides Patriot with the ability to process more complex algorithms that improve the system’s capabilities against advanced threats.