As the Russian newspaper Izvestiya noted, the system works with the same antennas already installed on the country's 250,000 cellular towers and could cover "entire regions like a dome that is impenetrable for satellite navigation signals." According to a spokesperson for the Russian Defense Ministry, the system has already been tested.
On the other hand, US equipment like Tomahawk missiles are already designed with onboard anti-jamming devices intended to keep them on course in the face of such interference, so it's unclear how effective a Pole–21 network would be. Deploying the system would also jam Russia's own communications and navigation systems. Still, one Russian military analyst who spoke with Izvestiya said that even milliseconds of jamming activity is enough throw off a missile's accuracy. Regardless of its efficacy, US Army officials seem to believe the missile jamming plan is part of a larger effort by Russia to prepare itself for a major attack.