_{A promotional brochure for surveillance and advertising technology, released by Wikileaks' Spy Files project.}

CORRECTION: Ars Technica reports that the Ukrainian government used cell phone tower dumps, not IMSI catchers, to conduct this surveillance.

The New York Times reports that the Ukrainian government is using advanced surveillance technology to track protesters in the streets.

The Ukrainian government used telephone technology to pinpoint the locations of cellphones in use near clashes between riot police officers and protesters early on Tuesday, illustrating that techniques that can be used to target commercial information can serve law enforcement as well.

People near the fighting between riot police and protesters received a text message shortly after midnight saying “Dear subscriber, you are registered as a participant in a mass disturbance.”

The phrasing echoed language in a new law making participation in a protest deemed violent a crime punishable by imprisonment. The law took effect on Tuesday.

The device used in Kiev is most likely what's known as an 'IMSI catcher', which tricks cell phones into thinking it is a cell phone tower. Any phone within a certain distance of the device will therefore send identifying information to it, allowing the operator to automatically compile a list of every person nearby with a cell phone. The systems can also capture web, phone, and text content from mobile devices, as well as automatically serve content like text messages to every phone within range. For that reason, advertisers and corporations increasingly use them to target people with location-specific pitches for products and services.

Back in 2012, a security researcher in the United States told an audience of hackers in New York that the NYPD routinely used IMSI catchers at the Occupy Wall Street protests, enabling the intelligence division to keep nearly perfect records of every person in attendance.

The intimidating surveillance tactic appears not to have succeeded in Kiev, however. Hours after the government sent the mass text message, "the riot police pushed past barricades of burned buses on Hrushevskoho Street near Parliament but were nonetheless met by a crowd of protesters in ski masks and helmets carrying sticks and ready to fight."

In the United States, the FBI uses the 'Stingray' IMSI catcher, made by the Harris Corporation. Documents released pursuant to a public records request strongly suggest the nation's most powerful domestic intelligence agency uses this invasive tool without warrants.