America’s Space Shield: How Satellites Protect National Security

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The satellites that protect U.S. national security deliver missile warning, navigation, communications and intelligence. Golden Dome, a homeland missile defense system the Defense Department is developing, may add weapons: the 2025 executive order behind it calls for plans to develop and deploy interceptors in orbit to shoot missiles down. Whether that can work, and at what cost, is an issue for Congress: President Donald Trump has put Golden Dome’s price at $175 billion, while the Congressional Budget Office has estimated more than $500 billion for a limited system of interceptors.

Civilians rely on the navigation satellites too. The Global Positioning System, or GPS, supplies timing that helps synchronize power grids and financial networks. The systems are also targets: jamming, false signals or an attack on a ground station can cut off the service while the spacecraft stays intact.

A warning is the start of a defense

The Space Based Infrared System, known as SBIRS, uses infrared surveillance for early missile warning and combines space hardware with ground hardware and software. Infrared is light invisible to the human eye that can be detected as heat. According to Lockheed Martin, the system’s missions also include supporting missile defense, describing battlefield conditions and technical intelligence.

The Space Development Agency, part of the U.S. Space Force, is responsible for rapidly delivering space-based capabilities to military forces.

For its newer tracking satellites, the Space Development Agency plans to collect infrared emissions from missile launches and from hypersonic objects, which heat up because of their high speed through the atmosphere. The satellites are intended to transmit the object’s path, called a missile track, to a ground processing facility either directly or through other tracking and transport satellites. That turns detection into information that can follow a moving threat, rather than just announce that something launched.

The Command and Control, Battle Management, and Communications system, hardware and software built for the ballistic missile defense system, combines information from sensors and weapon-control systems to help operators decide how to engage an incoming missile and coordinate several defenses. The Missile Defense Agency describes this system as enabling the president, defense secretary and combatant commanders to plan missile defense operations and manage networked sensors and weapons. The chain must connect a sighting to a usable track, a decision and an interception attempt.

President Donald Trump introduced Golden Dome, initially known as the Iron Dome for America, through an executive order on January 27, 2025. The executive order calls for developing and deploying space-based interceptors, as well as accelerating deployment of space-based tracking sensors. Interceptors would be weapons, a step beyond sensing a missile and relaying its track. In its August 18, 2026 update, the Congressional Research Service describes Golden Dome as an integrated homeland air and missile defense system under development.

The Congressional Research Service identifies cost and feasibility as issues for Congress. In May 2025, Trump said Golden Dome would cost $175 billion, and some observers have cited higher estimates, driven in part by the space-based interceptors. The Congressional Budget Office estimated a limited space-based interceptor system at more than $500 billion.

Space Force Gen. Michael Guetlein, who leads the Golden Dome office, reportedly announced in August 2026 that the Pentagon had established the program’s first operational site at Fort Story, Virginia, according to the Congressional Research Service. A first site is a development milestone, not evidence that a nationwide shield has been completed.

The same signals guide forces and civilian life

GPS supplies time as well as longitude, latitude and altitude, using precise timing signals from atomic clocks aboard its satellites. A receiver compares the satellites’ broadcast times and positions with its own clock, then uses signal travel time and the speed of light to calculate distances and determine its location.

The U.S. Space Force maintains GPS. The government provides civilian GPS access worldwide without direct user fees and publishes the information needed to develop user equipment. Free access to the signal does not mean a receiver, a phone or a commercial navigation service must be free.

GPS timing helps synchronize communications systems, power grids and financial networks. That makes loss of a trustworthy timing signal a problem even for users who are not trying to find their way anywhere.

Connections and intelligence reach beyond the horizon

Communications satellites support links beyond the line of sight, including connections to remote places without direct connectivity.

The Advanced Extremely High Frequency satellite system provides secure, protected and jam-resistant military communications through cross-linked satellites, according to Air & Space Forces Magazine. The Wideband Global SATCOM system can carry large amounts of data over long distances for military services and other government users. Jam-resistant describes a design capability, not a guarantee that communication can never be disrupted.

The National Reconnaissance Office collects and processes signals and imagery through its intelligence systems. The National Geospatial-Intelligence Agency analyzes imagery and geospatial information to describe physical features and geographically referenced activities for decision-makers, military personnel and first responders.

Who is responsible for the space system

The Space Force organizes, trains and equips its personnel, called Guardians, to support unified combatant commands such as U.S. Space Command. A unified combatant command has forces from two or more military departments and a broad, continuing mission. U.S. Space Command is responsible for U.S. military operations in space and is separate from the Space Force armed service.

Space Force functions include satellite communications, missile warning, navigation and timing, space access and protection against space and counterspace threats, such as weapons that degrade space services or destroy satellites. The National Reconnaissance Office designs, builds, launches and maintains intelligence satellites and belongs to both the intelligence community and the Defense Department. Responsibility follows the mission, so a military space system is not necessarily an intelligence satellite and an intelligence satellite is not necessarily operated by the Space Force.

From fiscal years 2021 through 2025, the National Reconnaissance Office purchased commercial imagery and the National Geospatial-Intelligence Agency purchased commercial analytic products, according to the Government Accountability Office. The government can obtain useful space information without building and owning the satellite that collected it. Some Space Force officials told the office about challenges with commercial data, including licensing costs and concerns over long-term access.

The satellites and their ground links can be targets

The Defense Intelligence Agency warns that adversaries can jam navigation and communications satellites used to command naval, ground and air forces, as well as crewed and uncrewed vehicles.

Jamming can prevent a satellite from receiving an intended uplink signal or interfere with reception by users on the ground. Spoofing sends a false signal with erroneous information to deceive a receiver. Losing a signal can interrupt service, while accepting a false one can leave a user acting on bad information. Keeping the spacecraft intact is not sufficient if its users cannot receive or trust what it sends.

The Defense Intelligence Agency also identifies physical and cyberattacks against supporting ground sites and infrastructure as threats to satellite services. A space defense consequently needs protection on Earth as well as in orbit.

A ground-based antisatellite missile can release a vehicle that homes in on a satellite and destroys it by striking it. The resulting debris can damage or destroy other satellites and crewed spacecraft, while avoidance maneuvers consume fuel and can shorten satellite lifetimes.

In 2021, NASA said debris from a destructive Russian antisatellite test had forced astronauts and cosmonauts aboard the International Space Station to take emergency safety measures. The crew was awakened and directed to close hatches to several station modules, then sheltered in their spacecraft during two passes through or near the debris cloud.

Many smaller satellites offer resilience, with a testing burden

The Space Development Agency designs a network of many satellites orbiting relatively close to Earth to keep functioning when individual satellites become unavailable. The agency describes its smaller satellites as cheaper and quicker to deliver and replace than some high-end defense spacecraft deployed in limited numbers.

The agency divides its network into layers. The planned Transport Layer connects communications satellites with one another, other spacecraft and ground stations through optical links. Those optical links use laser beams to transmit data between spacecraft and Earth. The Tracking Layer supplies sensing for advanced missile threats and connects to the Transport Layer to deliver threat indications and targeting data. Spreading the work across many satellites depends on the separate spacecraft and ground systems exchanging usable information.

The Government Accountability Office reported that five satellite contractors have faced challenges making their systems work with General Dynamics’ ground system. The Space Development Agency told the office that ground testing was not complete before the first launch in September 2025 of Tranche 1, a generation of the agency’s satellite architecture. For some satellites, the agency accepted the risk of finding defects once they were in orbit. The office warned that late discoveries could require rework and retesting, delay schedules or defer capability.

The Space Development Agency says Tranche 1 will begin providing warfighting capability in 2027, after its satellites are tested and raised to their operational orbits.

Funding and rules set different kinds of limits

Congress can decide whether and how to fund space-intensive defense initiatives and oversee their progress. For fiscal year 2027, the Space Force requested $71.3 billion: $59.2 billion in discretionary funding, which comes through regular appropriations, and $12.1 billion in mandatory funding it anticipated from a fiscal 2027 reconciliation bill, according to the Congressional Research Service’s review of budget documents. That is a request for the service, not an enacted appropriation or the total cost of every government use of satellites.

Public Law 119-21 is the 2025 budget reconciliation law often called the One Big Beautiful Bill Act. President Trump signed it into law on July 4, 2025.

Public Law 119-21, a budget reconciliation law, appropriated $24.4 billion in fiscal year 2025 funding for integrated air and missile defense, available until September 30, 2029. The law did not specify how much of that funding was for existing Defense Department programs and how much was for new work. That appropriation is not a complete lifetime price for Golden Dome or for national-security satellites as a whole.

The Government Accountability Office found that the Defense Department lacked a reliable estimate of the life-cycle cost of the Space Development Agency’s missile-warning and missile-tracking capability. Oversight therefore has to examine the cost of delivering the combined capability, not just individual spacecraft purchases.

Treaty rules set limits of a different kind. Article IV of the Outer Space Treaty bars nuclear weapons and other weapons of mass destruction in Earth orbit or stationed elsewhere in outer space. It also reserves the Moon and other celestial bodies for peaceful purposes and prohibits military bases, weapons testing and military maneuvers there. Those provisions are not a blanket prohibition on ordinary military communications, navigation or warning satellites in Earth orbit.

Direct-ascent antisatellite weapons strike a satellite without first putting the weapon or its components into orbit. In 2022, the United States announced a commitment not to conduct destructive direct-ascent antisatellite missile tests, according to the State Department’s later account. Satellite services remain vulnerable to interference despite the U.S. test commitment and the treaty’s weapons prohibitions.