Intense fighting in eastern Ukraine showed the benefits — and limitations — of HIMARS, experts say

• US-provided HIMARS rocket artillery aided Ukraine's rapid advance around Kharkiv in September.
• HIMARS destroyed Russian positions and depots, allowing Ukraine to retake a huge swath of territory.

If there is one weapon that symbolizes the Western arms that have helped Ukraine fight off Russia's invasion, it's the US-made M142 High Mobility Artillery Rocket System multiple rocket launcher, or HIMARS.

The success of Ukraine's recent counteroffensives has been partly attributed to HIMARS, of which the US has sent at least 20 to Ukraine.

But was HIMARS was really that effective? It was initially devastating, but Russian forces eventually learned how to cope with it, according to two US defense experts.

When HIMARS made its debut in Ukraine during the summer, it was hailed as a wonder weapon. GPS-guided rockets fired from the truck-mounted mobile launcher destroyed Russian headquarters and especially ammunition dumps, which helped curtail Russian artillery fire.

HIMARS paved the way for a stunningly successful Ukrainian counteroffensive in the Kharkiv region that began in early September and turned the balance of the war against Russia. It became evident that HIMARS was also harming Russian morale when Russian media ran dubious stories claiming the rockets had secret capabilities, such as changing their trajectory.

But when Ukraine used HIMARS in its counteroffensive against the city of Kherson on the Black Sea in southern Ukraine in late August, the outcome was different.

"It took Ukraine more than two months to retake the entire right bank of Kherson after beginning its offensive," Michael Kofman, director of the Russia Studies Program at CNA, and Rob Lee, a senior fellow in the Foreign Policy Research Institute's Eurasia Program, wrote in late December.

"Kherson reveals that the overall effect of HIMARS may be overstated, and its impact leveled off after the first two months of use on the battlefield," Kofman and Lee wrote.

Russian forces were able to sustain artillery fire and ultimately withdraw from Kherson with most of their equipment despite the threat from Ukraine's precision weapons, like HIMARS and specially designed artillery shells.

The adaptations Russia made in response to HIMARS "included displacing logistics hubs out of range, hardening command posts, and introducing decoys to make targeting more difficult," Kofman and Lee wrote.

Tactically, Russian forces at Kherson were in a difficult position: They held a bridgehead on the western bank of the Dnipro River, with only a few vulnerable ferries and a traversable dam to transport supplies and reinforcements from the main Russian positions on the east bank.

Despite Ukraine's employment of an impressive array of capabilities — from HIMARS and tanks to drones and special-operations forces — its offensive still ran into stiff opposition.

"The fighting was grinding, with high rates of attrition on both sides," according to Kofman and Lee. "Kherson offers a cautionary tale on the challenge of offensive maneuver against an entrenched opponent with sufficient artillery and air defense."

All of which raises a question: Was HIMARS so good or was Russia so bad? For example, the Russian army relies on a highly centralized logistic network that depends on a few railroad lines rather than on a more flexible truck transport to get supplies to the troops.

At the same time, Russia doctrine calls for massive artillery barrages. This led to huge ammunition dumps being positioned close to the front for convenience. It also meant that those huge stocks of artillery shells were within range of HIMARS rockets that — guided by GPS coordinates supplied by drones or satellites — could hit pinpoint targets 50 miles away.

"The requirements of high volume of fire were incompatible with adaptation to long-range precision strike," Kofman told Insider.

Russia failed to take precautions and was slow to adapt to long-range Western rockets and artillery supplied to Ukraine. Nonetheless, Russia eventually did adapt.

This raises another question: If much of HIMARS' success was due to Russian mistakes, how effective will these rockets against other adversaries in other potential conflicts, such as a Chinese invading of Taiwan?

For example, Ukrainian gunners enjoyed targeting data from US satellites that Russia couldn't attack for fear of escalating the war. Ukraine had access to US intelligence, surveillance, and reconnaissance "that played an important role, but due to political parameters was untouchable by Russia," Kofman said. "This is why you can't port findings easily into a war with direct US involvement."

Any military capability is most effective when introduced in sufficient quantity on the battlefield, but eventually the enemy adapts, Kofman said. "There are no silver bullets."

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.