Securing the electric power grid is among the highest priorities for critical infrastructure protection in the United States. In the past, power grid facilities have had varying degrees of access control and surveillance depending upon the facility type and location. These measures were largely focused on public safety (reflecting liability concerns) and preventing vandalism and theft. More recently, federal agencies, Congress, and the utility industry have focused greater attention on the vulnerability of the power grid, especially the high voltage transmission (bulk power) system, to terrorist attacks which could cause widespread, extended blackouts. Until 2013, the emphasis of analysts and policymakers was on power grid cybersecurity—protecting the computer controls and communication systems used to operate the grid. However, a 2013 rifle attack on an electric transmission substation in Metcalf, CA, shifted more attention to the physical security of power grid critical assets. In response to the Metcalf attack, as well as other grid incidents and findings from utility security exercises, Congress passed new legislation to strengthen power grid physical security and to facilitate recovery in the event of a successful attack. Congress also sought stronger physical security standards from the Federal Energy Regulatory Commission (FERC) under the commission's existing statutory authority to regulate the reliability of the bulk power system. FERC, in turn, ordered the North American Electric Reliability Corporation (NERC)—the not-for-profit organization responsible for ensuring grid reliability—to promulgate new requirements for the physical security of bulk power critical infrastructure. After consultation within the utility industry, NERC proposed new physical security standards in May 2014. FERC approved them, with minor changes, the following November. Since 2014, security risks to the power grid have become an even greater concern in the electric utility industry. Addressing them has remained a concern of Congress. An emphasis on physical risk to the power grid was underscored in September 2016 by another successful rifle attack on a transformer substation—in Utah. Reflecting ongoing security concerns, legislative proposals in the 115 th Congress include provisions directed at power grid physical security. Congress also continues its oversight of FERC's grid security activities and the implementation of NERC's physical security standards. This report examines changes to the physical security of the electric power grid since the promulgation of NERC's physical security standards. The report discusses the current risk environment for the bulk power system. It summarizes the key requirements of NERC's security standards, including its applicability to specific assets, implementation deadlines, and oversight. The report reviews observable changes in the utility sector related to physical security. It concludes with an overview of proposed legislation and a discussion of policy issues for Congress. This report focuses primarily on physical security efforts to prevent successful physical attacks on the bulk power system. For analysis of issues specifically related to power grid cyberattacks and cybersecurity, see CRS Report R43989, Cybersecurity Issues for the Bulk Power System , by Richard J. Campbell. This report also does not address issues related to security incident recovery or restoration, except in the context of preventive physical security. Grid security analysts and policymakers have long been aware of physical risks to bulk power critical infrastructure, especially to high voltage (HV) transformer stations and substations, which serve as key nodes within the electric transmission system. The 2013 Metcalf attack, in which an unknown perpetrator firing a .30 caliber rifle disabled a critical 500 kilovolt (kV) transformer substation, demonstrated that such facilities face real and potentially sophisticated threats. The September 2016 rifle attack on a 69 kV transformer substation in Utah—which reportedly left 13,000 rural customers without power for up to eight hours—showed that similar incidents could occur almost anywhere on the grid. A successful cyberattack on Ukraine's power grid in 2015, which was reportedly attributed to Russian hackers, showed that foreign entities could view power grids as attractive targets. A 2017 report from the National Academy of Sciences concludes: "While to date there have been only minor attacks on the power system in the United States, large-scale physical destruction of key parts of the power system by terrorists is a real danger. Some physical attacks could cause disruption in system operations that last for weeks or months." The persistent threat environment has been changing the perception of physical threats among power grid owners and operators. For example, surveys of electric utility employees show that their physical (and cyber) security concerns are growing. Exelon Corporation, one of the nation's largest utility holding companies, stated in its 2016 annual report Threat sources continue to seek to exploit potential vulnerabilities in the electric…utility industry associated with protection of sensitive and confidential information, grid infrastructure and other energy infrastructures, and such attacks and disruptions, both physical and cyber, are becoming increasingly sophisticated and dynamic.…The risk of these system-related events and security breaches occurring continues to intensify.… Xcel Energy, another major utility owner, likewise states in its 2016 annual report Our generation plants, fuel storage facilities, transmission and distribution facilities and information systems may be targets of terrorist activities… The potential for terrorism has subjected our operations to increased risks and could have a material effect on our business. Accordingly, electricity sector-wide security exercises conducted by NERC have simulated attacks on power grid critical assets combining both cyber and physical dimensions. These exercises are further discussed later in this report. On March 7, 2014, FERC ordered NERC to submit proposed reliability standards requiring transmission owners meeting certain criteria "to take steps or demonstrate that they have taken steps to address physical security risks and vulnerabilities related to the reliable operation" of the power grid. In its order FERC stated that physical security standards were necessary because "the current Reliability Standards do not specifically require entities to take steps to reasonably protect against physical security attacks." According to the FERC order, the new reliability standards were to require transmission owners or operators to perform a risk assessment of their systems to identify "critical facilities," evaluate the potential threats and vulnerabilities to those identified facilities, and develop and implement a security plan designed to protect against physical attacks on those identified critical facilities. The order required that each of these steps be verified by NERC or another third party qualified to review them. On May 23, 2014, NERC filed with FERC its proposal for mandatory physical security standards. On November 20, 2014, FERC approved the proposed standard, with minor changes, as NERC's new Physical Security Reliability Standard (CIP-014-1). Following publication in the Federal Register , FERC's order approving the standard became effective on January 26, 2015. FERC approved a revised version of the standard (CIP-014-2) on July 14, 2015. Required compliance for the standard began on October 1, 2015 with completion of the final parts required by November 24, 2016 for all applicable entities. The stated purpose of NERC's physical security reliability standard is "to identify and protect transmission stations and transmission substations, and their associated primary control centers, that if rendered inoperable or damaged as a result of a physical attack could result in instability, uncontrolled separation, or cascading within an interconnection." It applies to transmission owners with assets operating at 500 kV or higher as well as owners with substations operating between 200 kV and 499 kV if they meet certain interconnection or load-carrying criteria. The standard, generally referred to as "CIP-014," consists of six principal requirements (R1-R6), summarized as follows: R1. Risk assessments by transmission owners to identify critical transmission facilities; R2. Independent third party verification of risk assessments conducted under R1; R3. Requirement for transmission owners with critical facilities identified under R1 but not under their operational control to notify the transmission operator of these facilities; R4. Mandatory threat and vulnerability assessments for critical facilities conducted by transmission owners and operators; R5. Development, documentation, and implementation of physical security plans to protect critical facilities; and R6. Independent third party review of the threat and vulnerability assessments performed under R4 and security plans developed under R5. The standard also lays out a process for compliance monitoring and assessment including audits, self-certifications, spot checking, violation investigations, self-reporting, and handling complaints. The new standard is enforced by NERC or another Regional Entity under a penalty review policy for mandatory reliability standards approved by FERC subject to the Commission's enforcement authority and oversight under the Energy Policy Act of 2005 ( P.L. 109-58 ). Monitoring of compliance with the standard is further discussed below. Three entities play key roles in standards oversight and implementation support for bulk power physical security. NERC and FERC directly oversee implementation of the CIP-014 standards, while the Department of Energy (DOE) plays a supporting role in helping bulk power asset owners to protect their critical assets. As stated above, with oversight by FERC, NERC has the authority to develop, oversee, and enforce implementation of the CIP-014 physical security standard. NERC carries out these functions together with the eight Regional Entities (e.g., Midwest Reliability Organization) with which NERC has agreements to delegate its authority to monitor and enforce reliability standards compliance. Collectively, NERC and the Regional Entities comprise the Electric Reliability Organization (ERO) Enterprise. In general, NERC employs a risk-based framework to monitor compliance of all its grid reliability standards on the belief that monitoring and enforcement must be "right-sized" based on considerations including risk factors and management practices related to detecting, assessing, mitigating, and reporting of noncompliance. As reliability risk is not the same for all registered entities, the Framework examines [bulk power system] risk of registered entities both collectively and individually, to determine the most appropriate [Compliance Monitoring and Enforcement Program] tool to use when monitoring a registered entity's compliance with NERC Reliability Standards.