The Global Positioning System guides our ships at sea. It’s the centerpiece of the new next-gen air traffic control system. It even timestamps the millions of financial transactions made across the world each and every day.

And it's at extreme risk from criminals, terrorist organizations and rogue states -- and even someone with a rudimentary GPS jammer that can be bought on the Internet for 50 bucks, said Todd Humphreys, an expert on GPS with the University of Texas.

“If you’re a rogue nation, or a terrorist network and you’d like to cause some large scale damage -- perhaps not an explosion but more an economic attack against the United States -- this is the kind of area that you might see as a soft spot,” he told Fox News.

Humphreys was the keynote speaker at a conference of world experts organized by the UK - ICT Knowledge Transfer Network in London yesterday. His predictions for what lies ahead with this emerging threat were dire.

For example, in 2010, UK researchers aimed a low-level GPS jammer at test ships in the English channel. The results were stunning: Ships that veered off course without the crew’s knowledge. False information passed to other ships about their positions, increasing the likelihood of a collision. The communications systems stopped working, meaning the crew couldn’t contact the Coast Guard. And the emergency service system -- used to guide rescuers -- completely failed.

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Then, there’s the incident with the U.S. drone lost over Iran. Humphreys believes that by using simple jamming technology, Iranian authorities confused the ultra-sophisticated RQ-170 spy drone to the point that it went into landing mode. The drone’s Achilles heel? It had a civilian GPS system -- not a military-grade encrypted model. It didn’t take much to blind it and force it down.

Another level of rapidly-emerging threat is so-called “spoofing." Unlike a jammer, which blocks or scrambles GPS signals, a “spoofer” mimics information coming from a satellite. It can make an aircraft, ship or other GPS-guided device think it’s somewhere that it’s not.

Humphreys says organized crime is already attempting to exploit the possibilities. Gangs could hijack a container truck full of high value goods, and through spoofing, make its owner think it’s on its way to the intended delivery point -- instead of to the gang’s warehouse.

“The civil GPS signal's completely open and vulnerable to a spoofing attack, because they have no authentication and no encryption," Humpheys told Fox News. "It’s almost trivial to mimic those signals to imitate them and fool a GPS receiver into tracking your signals instead of the authentic ones.”

Hijacking a cargo container is one thing. Spoofing the global financial system is quite another. In his London presentation, Humphreys warned about another emerging GPS threat -- the worldwide network of stock and commodity trades.

Every trade is time-stamped using GPS clocks. Computer programs monitor those time stamps down to the millisecond. If something seems amiss, many programs are designed to pull out of the market. Humphreys says a hacker could fairly easily interfere with those time stamps, triggering trading programs, creating a sudden liquidity crisis and potentially a mini market crash.

Then, there’s the high-dollar reward of manipulating time. An unscrupulous trader -- or criminal organization could make millions by delaying time even by a heartbeat.

“You’re able to match the prices between the networks in a way that’s different from everyone else in the world,” Humphreys said. “Everyone else in the world might be 20 milliseconds off and you happen to know the actual timing. And so you’re able to buy low in one market and sell high in another market.”

The system is so vulnerable to attack because signals coming from the network of GPS satellites orbiting the earth are very weak. They’re about 12,000 miles away. It doesn’t take much to disrupt them.

A landmark study in the UK published Wednesday, Feb. 22, found GPS jammers in widespread use on that nation’s highways. While it has not yet been studied in the U.S., it’s believed an equal or greater problem exists in America.

The devices are illegal in the States, yet they are readily available over the Internet for as little as $50. People use them to avoid tolls, evade a snooping spouse, or use a company vehicle for something other than its intended purpose. And that sometimes has unintended consequences.

Recently, the new GPS landing system at Newark airport, just outside New York City, was crashing several times a week, forcing airliners to switch to a backup system. Airport officials were baffled. It turns out some fellow was moonlighting in a GPS-tracked company van. He was using a jammer to obscure his movements. Every time he drove by Newark airport, he took down the landing system.

As much as GPS jammers or spoofers can cause havoc to multiple systems, Humphreys sees a conflict between the growing integration of GPS technology and our personal lives.

He says devices that interfere with GPS might actually have a legitimate use: Protecting a person’s privacy.

“People have a right to be private in their lives,” he said. “But with GPS tracking devices the size of a small dot being able to place them surreptitiously on your friends -- they’re going to want to resort to some sort of jamming or spoofing as a defense against that kind of invasion of privacy.”