CNN reported that Russia has been increasingly employing electronic jammers to distort the precision of Ukraine’s High Mobility Artillery Rocket Systems. The jammers distort the mobile rocket by throwing off the targeting system’s GPS guide causing the rockets to miss their targets. 

US-manufactured HIMARS have been Ukraine’s key weapon in the war: described as the “most revered and feared” weapon in Ukraine’s arsenal. Ukraine currently employs 18 American HIMARS with another 20 anticipated to be received soon, with a steady influx of GMLRS shells (which serve as munition for the HIMARS) from the US’ routine packages of military aid.  

Read more: Ukraine launches 12 HIMARS missiles at bridge in Kherson
 
The rocket systems have been pivotal for Ukraine’s deterrence capacity: allowing them to fire salvos of six successive missiles with only a 3-meter margin of error in precision targeting sites as far as 80 kilometers away. 

However, over the past few months, Russians have mastered the art of jamming technology rendering the American masterpiece increasingly less effective.

Read more: HIMARS are useless, Russia has "remarkably adapted": NYT 

Electronic jamming and countermeasures

Informed Western sources told CNN that American and Ukrainian officials have been persistently trying to override Russia’s jamming technology by updating the HIMARS software. However, the updated measures have been met with more sophisticated Russian jamming technology. 

A Pentagon official described it as a “constant cat-and-mouse game”: whereby the Americans try to countermeasure only for the Russians to then counteract that countermeasure. To sustain the efficacy of the HIMARS, the Pentagon official added, constant tweaking needs to be made: noting that software updates to the HIMARS have been done as recently as this week. 

Read more: Pentagon leak: Kirby confirms US Special Forces presence in Ukraine

“If their jamming gets more sophisticated, then your countermeasures have to get more sophisticated,” CNN quoted a British official saying.

However, CNN reported, citing a US official, that there’s a limited number of configurations of software updates that can be coded into the HIMARS: thus, the electronic battle of jamming and de-jamming is a losing game for Kiev and their allies given the limited margin of maneuver which the HIMARS software allows for.   

The more efficient alternative tactic is switching up the medium and attacking the hardware seat of the jammers, which the American official confirmed was underway. The US is reportedly assisting and advising Ukrainian forces on identifying and destroying the Russian jamming tech, according to the Official cited in the CNN report. 

Furthermore, according to the recently leaked Pentagon documents, identifying and destroying Russian jammers has been categorized as a “high priority” effort for the US over recent months. 

Read more: US leaked docs make Ukraine troops look like proxy war pawns: Expert

“We will continue to advocate/recommend that those jammers are disrupted/destroyed to the maximum extent possible,” the document reads. 

On-Field Practical Significance

Russia’s use of electronic warfare potential has increased exponentially since the onset of the war. The tactic which is cheap and easy to implement proved to be highly effective in incapacitating Ukraine’s prized possession weapon: significantly stifling Ukraine’s advancement efforts. 

The report contends that the long-awaited Ukrainian spring counter-offensive relies heavily on HIMARS to make headway through Russian lines: such that the HIMARS are necessary to make effective deep strikes.

“It’s one thing to be able to hold the Russians off where they are right now. It’s another thing to drive them out,” retired US Army Brig. Gen. Steven Anderson told CNN. “They’re dug in, they’ve been there for a year.”

Read more: Ukraine shelling of Russia reliant on US precision targeting: WashPo

The jamming of the mobile HIMARS was assessed to be very "significant" to the development of the war by a drone pilot on the eastern front, ever since the Russians had started doubling down on jamming efforts last November. 

HIMARS' effectiveness, according to a second drone operator in the southern Kherson region, has considerably diminished although they are still highly important and relied upon, they are no longer as dominant as they once were.