By Christopher Mims

The world is filling up with GPS dead zones.

Nations and individuals alike are deploying cheap but increasingly sophisticated electronic-warfare systems, mostly to thwart attacks by drones and smart munitions. Some jammers, which drown out the relatively weak GPS signals from satellites 12,000 miles up in orbit, are as small as a cellphone and cost less than $100.

Jamming had become commonplace along the Russia-Ukraine border, but now the Strait of Hormuz, through which 20% of the world's oil is transported, is besieged by such electronic attacks.

"GPS denial" is one of many factors making that waterway treacherous to navigate on account of America's new war with Iran, says Ami Daniel, chief executive of maritime intelligence company Windward.

In Northern Europe, flights have been turned back when GPS signals were jammed near airports. In one instance, a plane carrying the European Commission president was forced to divert to another airfield. And according to written testimony submitted to Congress, the hit rate of one American satellite-guided weapon fell from 70% to 6% in Ukraine after Russia instituted widespread GPS jamming. Russia and other countries also spoof GPS, broadcasting fake signals to throw off receivers.

The good old Global Positioning System -- built by the U.S. during the space race and dependent on signals so weak it's a miracle any device can detect them -- is showing its age.

Many providers of financial and telecommunications systems, commercial air travel and other vital services are seeking suitable alternatives. Engineers have been working on some for years, and in some cases decades. Some are already in use, or are on the cusp of widespread commercialization.

Miniaturizing missile guidance

Long before America had a cluster of 31 GPS satellites blanketing the globe, the Defense Department needed a way to guarantee ballistic missiles could find their targets. Engineers looked to inertial navigation systems found aboard early rockets.

They use gyroscopes to measure acceleration in any direction and integrate changes in velocity using a computer. As long as the system knows its starting position on a map, and factors in wind and other variables, it can determine its location with a high degree of accuracy.

Modern versions have traded physical gyroscopes for optics. They aren't jammable like GPS, but the best ones can cost millions of dollars, so their customers are mostly militaries and operators of shipping or airline fleets.

Mario Paniccia, chief executive of Anello Photonics, wants to turn bulky and expensive inertial navigation systems into microchips cheap and small enough to fit inside a phone.

By replacing fiber optics and lasers with chip-based optical electronics, his company has already shrunk such systems to an unprecedented degree. Anello's latest generation is a one-inch cube, which draws so little power that it can be used on drones.

Sensing Earth's magnetism

Under our feet, massive anomalies distort our planet's magnetic field: Manhattan-size rocks, colossal buried meteorites, chunks of crust that solidified when the poles were flipped.

At the quantum-sensing firm SandboxAQ, an Alphabet spinoff, Luca Ferrara heads a team developing a system that can help ships and airliners navigate in GPS-denied areas by detecting Earth's distinctive magnetic anomalies.

Using supersensitive, quantum-based magnetic sensors, it's possible to read that field the way a compass needle does and match those variations to pre-existing maps of them.

Other startups, including Q-CTRL in Australia, are developing similar systems. They have the advantage of being unjammable, and the disadvantage of being not terribly accurate compared with GPS. That can be fine for ships and planes, says Ferrara, or for smart munitions that just need to get close enough to their targets that they can switch to computer vision.

Eyeing the terrain with cameras

Visual navigation, matching what a camera sees to the landmarks on a map, has been in use for decades. In the war between Russia and Ukraine, human guidance of drones is increasingly being replaced with AI-powered target recognition and visual navigation.

Among the countless startups in this space is Brooklyn, N.Y.-based Vermeer, which began by building visual navigation systems for cinematography drones. When that business dried up in 2019, founder Brian Streem had a chance meeting with an investor and pivoted to defense applications. He has spent most of the past two years in Kyiv, Ukraine, and counts parts of the U.S. armed forces among his customer base.

Streem says that while cruise missiles have used visual navigation since the 1950s, modern computer processing makes new systems vastly more powerful and power-efficient. The other components have improved, too: "The map data is better, the resolution of the cameras is better," says Streem. "Everything has increased a thousandfold to make it actually work."

Combining the various options

The biggest issue with all these alternatives is that GPS, when it works, is ubiquitous and highly accurate. No alternative, by itself, can do everything it does.

Take inertial navigation systems. As with sea captains of old, if a heading or speed estimate is a tiny bit wrong, that can mean increasingly inaccurate positioning over time.

Existing systems on cargo ships and tankers are built to take over from GPS for up to a day. "They were not designed to be completely without GPS for a week or two," says Windward's Daniel.

Every expert I talked to said that the future of non-GPS navigation is multiple, complementary tools.

Vatn Systems, a Rhode Island startup, makes underwater autonomous vehicles that range in size from a 50-pound hand-held to an 800-pounder that's 20 feet long. Their missions include underwater surveillance and torpedo-like delivery of explosives.

The company is testing Anello's inertial navigation as a way for its micro subs to travel miles underwater -- where GPS doesn't work -- and to navigate on the surface in GPS-denied areas.

The key, says Vatn co-founder Nelson Mills, is to use whatever signals are available and appropriate, including sonar to home in on targets, and even technicians manually entering location data at the start of a sub's journey. Inertial navigation is always the foundation, but it must be supplemented, he adds.

These new alternatives to GPS tech will only get smaller and cheaper. But to make their way into the civilian world, not just personal electronics but delivery drones, self-driving cars, cruise ships and airliners, they've got to run a gantlet of tests.

It might take years for SandboxAQ's magnetic sensors to make their way into commercial airliners, as they await regulatory approval. But they could be in military service in 18 months, says Ferrara.

Wars, as ever, are crucibles for rapid development -- and adoption -- of new tech.

Write to Christopher Mims at christopher.mims@wsj.com

(END) Dow Jones Newswires

March 06, 2026 12:00 ET (17:00 GMT)

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