What Is Diplomatic Security and How Does DSS Work?

Diplomatic security is the framework the U.S. government uses to protect its foreign policy operations, personnel, facilities, and information from threats at home and overseas. The work is led by the Bureau of Diplomatic Security (DS) within the Department of State, which deploys thousands of security professionals across more than 270 locations worldwide and covers everything from embassy construction standards to counterterrorism investigations, cybersecurity, and protection of the Secretary of State.¹

Who Runs Diplomatic Security

DS is the Department of State’s law enforcement and security arm. It is led by an Assistant Secretary of State.² Its operational workforce is the Diplomatic Security Service (DSS), which includes more than 2,500 special agents, security engineering officers, security technical specialists, and diplomatic couriers. With offices in more than 30 U.S. cities and over 270 locations abroad, DS is the most widely represented U.S. federal law enforcement agency in the world.³

DSS special agents hold a dual identity: they are both Foreign Service officers and federal law enforcement professionals. Federal law authorizes them to carry firearms, execute search and arrest warrants, and make warrantless arrests for felonies committed in their presence. The same statute defines their protective and investigative duties, from guarding the Secretary of State to investigating passport fraud and protecting foreign missions on U.S. soil.⁴

The Office of Mobile Security Deployments (MSD) functions as the department’s tactical response unit. MSD teams deploy to embassies and consulates facing heightened threats from terrorist attacks, political unrest, or natural disasters, and they augment protective details for senior officials in high-risk environments.⁵

Protecting Embassies and Consulates

Physical security of U.S. diplomatic facilities rests on layered defense. The legal foundation is the Omnibus Diplomatic Security and Antiterrorism Act of 1986, which made the Secretary of State responsible for the security of all diplomatic operations and personnel.⁶ Construction standards for new facilities are codified at 22 U.S.C. § 4865.

Under that statute, newly acquired diplomatic facilities in locations rated above certain thresholds on the Security Environment Threat List must meet blast-performance standards equivalent to a building set back at least 100 feet from its property perimeter. Where a full 100-foot setback is impractical, the Secretary of State can approve engineering measures achieving equivalent blast protection, or waive the requirement if national interest demands it, provided Congress is notified in writing beforehand.⁷ Compounds incorporate anti-ram vehicle barriers, reinforced walls, and controlled perimeter zones designed to absorb the force of an explosive attack.

At each post, a DSS special agent serves as the Regional Security Officer (RSO), the ambassador’s principal law enforcement and security advisor.⁸ The RSO runs every security program at the post: access control, emergency planning, criminal investigations involving embassy staff, coordination with host-nation police and intelligence services, management of the local guard force, and direction of the Marine Security Guard detachment.

Marine Security Guards stand duty around the clock. They control access within the facility, safeguard classified information and equipment, monitor surveillance systems and fire alarms, and serve as the focal point for emergency communications, protecting facilities from hostile demonstrations and helping evacuate diplomats and families during crises.⁹ The outer perimeter is handled by local guard forces, typically citizens of the host nation. They number more than 35,000 worldwide and patrol embassy grounds, inspect vehicles and visitors, and respond to alarms.¹⁰

Protecting People

DS provides protective details for specific senior officials and visiting dignitaries. The Secretary of State receives around-the-clock protection anywhere in the world.¹¹ The U.S. Ambassador to the United Nations also receives continuous coverage.¹² Federal law authorizes DSS to protect departing Secretaries of State for up to 180 days after they leave office, along with anyone designated by the President or President-elect as the incoming Secretary.⁴

DSS also protects visiting foreign dignitaries below the head-of-state level while they are on U.S. soil, deploying hundreds of agents on domestic and overseas details each year.¹² For U.S. ambassadors and chiefs of mission at high-threat posts overseas, MSD teams from Washington provide tactical augmentation and train embassy staff in defensive measures.

Moving Classified Material

Diplomatic couriers move classified government material across international borders. The cargo they escort in diplomatic pouches goes well beyond paper files; it can include thousands of pounds of equipment and construction materials bound for sensitive posts.¹³ Couriers travel by air, sea, and land, maintaining an unbroken chain of custody from the Department of State to embassies and consulates worldwide.

Legal protection for the pouch comes from Article 27 of the Vienna Convention on Diplomatic Relations, which states that a properly designated diplomatic bag “shall not be opened or detained.”¹⁴ The United States treats X-ray screening as the electronic equivalent of opening a pouch, so it neither X-rays nor physically searches properly designated foreign diplomatic pouches, and it treats any foreign government doing so to U.S. pouches as a serious breach of international law. To qualify, a pouch must bear visible external markings identifying it as a diplomatic pouch, carry the official seal of the sending government, and be properly addressed. There are no internationally recognized limits on pouch size, weight, or quantity.¹⁵

Investigations and Law Enforcement

DS carries broad federal law enforcement authority beyond its protective mission. A major focus is passport and visa fraud, which DSS investigators pursue both in the United States and at overseas posts.³ Fraudulent travel documents are federal felonies, and these cases frequently uncover connections to other criminal activity. Agents also investigate identity theft and document fraud affecting State Department programs, transnational human trafficking, and federal offenses committed within the special maritime and territorial jurisdiction of the United States.⁴

Overseas, DSS agents are often the senior American law enforcement representative in the country. They help other U.S. agencies locate fugitives who have fled abroad and investigate crimes committed against State Department employees and their families. Domestically, DSS details officers to FBI Joint Terrorism Task Forces to share intelligence and coordinate counterterrorism operations.

Victims of crimes DSS investigates, including domestic violence, sexual assault, human trafficking, terrorism, and identity theft, can get help through the Victims’ Resource Advocacy Program. VRAP staff explain the legal process, stay engaged with victims as cases move through the courts, and connect them with housing, legal representation, therapy, and medical care.¹⁶

Cybersecurity

The Directorate of Cyber and Technology Security (CTS), established within DS in 2017, is the bureau’s hub for detecting, analyzing, and responding to cyber threats targeting the Department of State. CTS maintains a 24/7 watch over the department’s global cyber infrastructure, handling incident response, in-depth analysis of intrusions, cyber threat intelligence reporting, and independent vulnerability assessments. It serves as the department’s liaison to US-CERT and works with the FBI, NSA, and other federal law enforcement and intelligence partners. A separate component, the Foreign Affairs Cybersecurity Center, monitors suspicious activity and tracks emerging threats across the broader foreign affairs community.¹⁷

Working With The Private Sector And Foreign Partners

The Overseas Security Advisory Council (OSAC) connects DSS with private-sector security professionals from U.S. organizations operating abroad. Information moves both ways: the private sector shares on-the-ground insights about local conditions, and DSS provides threat analysis, alerts, and crisis support. OSAC has over 5,400 organizational members and 18,000 individual members, with more than 150 country chapters worldwide.¹⁸ For American businesses with employees abroad, OSAC is one of the most practical touchpoints with the diplomatic security apparatus.

The DSS Office of Antiterrorism Assistance (ATA) is the U.S. government’s primary provider of counterterrorism training and equipment to foreign law enforcement. Since Congress created the program in 1983, ATA has trained more than 165,000 law enforcement officials and first responders from over 150 countries. Courses cover police operations, protection of national leaders, tactical response, explosives handling, crisis management, and chemical, biological, radiological, and nuclear response, and every course emphasizes rule-of-law principles and respect for human rights. ATA also runs the Special Program for Embassy Augmentation and Response (SPEAR), which builds dedicated quick-reaction forces of host-nation police trained to respond around the clock to attacks on U.S. diplomatic facilities in high-threat environments.¹⁹

The Rewards for Justice program, administered by DS under 22 U.S.C. § 2708, pays for information leading to the arrest or conviction of individuals involved in international terrorism, preventing terrorist acts, identifying key terrorist leaders, or disrupting terrorist financing.²⁰ Congress has expanded its scope beyond counterterrorism to cover foreign interference in U.S. elections, state-sponsored cyber attacks violating the Computer Fraud and Abuse Act, activities supporting the North Korean regime, international narcotics trafficking, transnational organized crime, and serious violations of international humanitarian law.²¹

What Happens After A Serious Incident

When a serious security incident causes loss of life, significant injury, or major property destruction at a U.S. diplomatic mission abroad, federal law requires the Secretary of State to convene a Security Review Committee, formerly the Accountability Review Board, within 60 days.²² The same requirement applies to serious breaches of security involving foreign intelligence operations directed at a mission. The Secretary may extend the deadline by another 60 days, and may delay proceedings further if a committee would compromise intelligence sources or methods.

These committees examine the facts and circumstances of the incident and produce a written report with findings and recommendations. The framework was established by the 1986 Omnibus Diplomatic Security and Antiterrorism Act and amended in 2022 to rename the boards and update their procedures.²² Recommendations from past reviews have driven changes to embassy construction, staffing, and emergency response protocols.

1
U.S. Department of State. Bureau of Diplomatic Security
2
U.S. Department of State. Leadership – Bureau of Diplomatic Security
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U.S. Department of State. Bureau of Diplomatic Security – What We Do
4
Office of the Law Revision Counsel. 22 USC 2709 – Special Agents
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U.S. Department of State. Mobile Security Deployments (MSD) Factsheet
6
Congress.gov. Public Law 99-399 – Omnibus Diplomatic Security and Antiterrorism Act of 1986
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Office of the Law Revision Counsel. 22 USC 4865 – Security Requirements for United States Diplomatic Facilities
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U.S. Department of State. Regional Security Officers Factsheet
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U.S. Department of State. 60 Years and Still Going Strong – New Marine Security Guard Agreement Signed
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U.S. Department of State. Diplomatic Security – Definition, Scope, and Agency Roles
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U.S. Department of State. Protecting the Secretary of State
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U.S. Department of State. Protecting People
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U.S. Department of State. Diplomatic Couriers
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United Nations. Vienna Convention on Diplomatic Relations, 1961
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U.S. Department of State. Diplomatic Pouches
16
United States Department of State. The DSS Victims Resource Advocacy Program – Empowering Victims, Providing Worldwide Support
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U.S. Department of State. Cybersecurity
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U.S. Department of State. Overseas Security Advisory Council
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U.S. Department of State. Antiterrorism Assistance Program
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U.S. Department of State. Rewards for Justice
21
Office of the Law Revision Counsel. 22 USC 2708 – Department of State Rewards Program
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Office of the Law Revision Counsel. 22 USC 4831 – Security Review Committees