Can satellites actually see naval mines underwater?

GEOSPATIAL INTELLIGENCE

David Dong

8/26/20265 min read

On August 25, President Donald Trump said that the U.S. Navy had removed or detonated all mines in the international waters of the Strait of Hormuz.

Then came the most interesting line:

Through the U.S. Space Force, he said, the United States was watching “every square inch” of the Strait. (investing.com)

The statement arrived at a critical moment. Preliminary Vortexa data indicated that oil transits through the Strait had fallen to approximately five million barrels per day, compared with more than 20 million barrels per day before the conflict. (investing.com)

But can satellites really detect naval mines?

Not in the way the statement might suggest.

Satellites usually cannot see submerged mines

Most naval mines are deployed underwater. Conventional optical satellites cannot see through the sea surface with sufficient reliability, while space-based synthetic aperture radar, or SAR, primarily observes the surface and objects interacting with it.

The satellites are therefore more likely to be watching the act of minelaying rather than the mine itself.

That means detecting suspicious vessels, tracking their movements, identifying radio emissions, and recognizing behavioral patterns associated with a possible minelaying operation.

The exact U.S. architecture being used in the Strait has not been publicly disclosed. But based on known commercial and military capabilities, it could combine several layers of data.

Layer one: SAR finds vessels in darkness and cloud

SAR satellites actively transmit microwave signals and measure their reflections.

Unlike optical satellites, they can operate at night and through clouds. That makes them particularly valuable for detecting ships attempting to operate under poor visibility or outside normal observation windows.

SAR can reveal a vessel even when it is not broadcasting its identity. It may also detect wakes and changes in a ship’s speed or direction.

But SAR generally provides detection, not certainty.

An image may show that a vessel exists at a particular location. It does not automatically reveal the vessel’s identity, purpose, or cargo.

Layer two: AIS establishes the normal picture

Most commercial vessels broadcast identification, position, heading and speed through the Automatic Identification System.

Satellite AIS provides the cooperative traffic baseline.

When a vessel appears in SAR imagery but has no corresponding AIS signal, analysts have a potential “dark vessel.” That does not necessarily mean the ship is hostile—AIS can disappear for technical or legitimate operational reasons—but it creates a reason for further investigation.

The key is not AIS alone. It is the difference between what AIS reports and what other sensors observe.

Layer three: RF satellites locate transmitting vessels

Turning off AIS does not necessarily make a ship electronically invisible.

Navigation radar, satellite phones, and maritime radios may continue transmitting. Commercial RF-monitoring satellites can detect and geolocate some of these emissions.

The United Kingdom’s Amber program, for example, was designed to identify satellite-phone and navigation-radar signals from vessels that had disabled AIS. (gov.uk)

HawkEye 360 has built a commercial constellation around a similar concept: detecting, characterizing, and geolocating RF emissions from space.

These systems do not guarantee that every dark vessel will be found. A ship practicing strict emissions control may produce no usable signal, and attributing an RF emission to a specific vessel can require additional evidence.

But RF detection can add a crucial clue.

Layer four: optical imagery confirms identity

Once SAR or RF data identifies a suspicious location, high-revisit optical satellites can be tasked to obtain a clearer image.

That image may help analysts estimate the vessel’s size, class, deck configuration, or identity.

BlackSky says its on-demand service typically delivers imagery in approximately 90 minutes. That does not prove the same latency applies to military operations in the Strait, but it illustrates how quickly commercial constellations can now support time-sensitive missions. (info.blacksky.com)

The final product is not one perfect image. It is a sequence:

SAR detects a vessel.
AIS shows no corresponding identity.
RF data locates an active transmitter.
Optical imagery helps confirm the target.
Analytics examine its route, speed, and behavior.

A vessel moving slowly at night, repeatedly stopping near shipping lanes, or following an unusual pattern could then be flagged for closer surveillance.

The dark-vessel model has already been demonstrated

This type of commercial data fusion has been operating for years.

In March 2020, the Iranian tanker Romina disappeared from AIS tracking while traveling toward Syria.

HawkEye 360 later geolocated maritime VHF signals near the Baniyas refinery. AIS records showed no vessels in the immediate area. The following day, TankerTrackers used Planet optical imagery to identify Romina and several other Iranian tankers near the refinery. (satnews.com)

The case did not involve minelaying. But it demonstrated the underlying method:

Combine cooperative tracking, RF detection, satellite imagery, and open-source analysis to find a vessel that does not want to be found.

The Space Force may be the integrator, not the sole sensor operator

It would be misleading to imagine that the Space Force owns every satellite involved or is operating a single purpose-built “mine detection constellation.”

The more likely model is a hybrid architecture combining classified government systems, commercial satellite services, intelligence-community resources, and data from airborne or maritime platforms.

The Space Force’s Tactical Surveillance, Reconnaissance, and Tracking program—TacSRT—already uses commercial and publicly available data to produce surveillance and planning products for U.S. combatant commands.

Meanwhile, the National Reconnaissance Office has established major commercial procurement channels.

The procurement structure is increasingly clear:

The government does not need to build every sensor. It can purchase data, task commercial constellations, and integrate the results into a military decision-making system.

“Every square inch” is still deterrence language

Trump’s phrase should not be interpreted as a literal technical description.

Publicly known low-Earth-orbit commercial constellations provide repeated coverage, not uninterrupted observation of every point in the Strait. Their role is better understood as a wide-area tripwire.

One sensor identifies an anomaly. Another is tasked to investigate. Aircraft, drones, ships or other intelligence systems then take over.

This also makes latency more important than image resolution alone.

Quilty Space has reported that maritime users typically expect intelligence within 30 minutes of collection. The commercial competition is therefore shifting from “Who can produce the sharpest picture?” to “Who can detect, process, fuse and deliver an answer while it is still actionable?” (spacenews.com)

That does not mean the publicly known U.S. system in Hormuz necessarily operates within 30 minutes. Its actual performance remains classified.

Space-based monitoring has hard limits

There are at least three.

First, satellites cannot reliably confirm that every submerged mine has been removed. Mine clearance still depends on naval vessels, sonar, remotely operated systems, divers and other specialized assets.

Second, underwater minelaying is far harder to observe from space. Submarines and uncrewed underwater vehicles can deploy mines without creating an obvious surface signature.

Third, suspicious behavior is not proof of hostile intent. A ship slowing down, changing course or operating without AIS may have many explanations. Military action requires a much stronger chain of identification and attribution than a commercial anomaly alert.

Space-based surveillance is therefore only the opening layer of the counter-mine mission.

It can help answer:

Which vessel was present?
Where did it travel?
When did it stop?
What signals did it transmit?
Did its behavior match a known pattern?

It cannot, by itself, clear the waterway.

The business is moving from pixels to answers

This may be the most important commercial-space lesson.

The traditional satellite-imagery business sold pictures: customers purchased an image and conducted their own analysis.

That model has not disappeared. But the highest-value part of the market is moving upward.

Customers increasingly want:

A continuously updated vessel identity
An alert when a ship disables AIS
A warning when its route becomes abnormal
A fused assessment from several sensors
An answer delivered quickly enough to support action

HawkEye 360 is not simply selling maps of RF energy. Maritime intelligence companies are not simply reselling AIS points. Programs such as TacSRT are designed to turn commercial sensing and publicly available information into operational planning products.

Pixels are becoming cheaper. Timely, trusted answers are becoming more valuable.

Trump’s statement should not be read as proof that the Space Force can see every mine beneath the Strait of Hormuz.

It points to something more significant:

Space-based intelligence has moved beyond taking pictures. It is becoming a near-real-time system for finding anomalies, combining evidence and directing the next sensor—or the next military asset—toward the target.

The sensor is only the entrance.

The processing chain is the real product.