The fighting in eastern Ukraine demonstrated the advantages and limitations of HIMARS

• US HIMARS rocket artillery aided Ukraine’s rapid advance around Kharkiv in September.
• HIMARS destroyed Russian positions and warehouses, allowing Ukraine to retake a large part of the territory.
• But Russian forces adapted and managed to limit the effectiveness of HIMARS in the fighting around Kherson.

If there is one weapon that symbolizes the Western weapons that helped Ukraine fight the Russian invasion, it is the American M142 High Mobility Artillery Rocket System, or HIMARS.

The success of recent Ukrainian counteroffensives is partly attributed to HIMARS, of which the US has deployed at least 20 to Ukraine.

But was HIMARS really that effective? It was devastating at first, but Russian forces eventually learned how to deal with it, according to two U.S. defense experts.

When HIMARS debuted in Ukraine over the summer, it was hailed as a wonder weapon. GPS-guided rockets fired from a truck-mounted mobile launcher destroyed the Russian headquarters, especially the ammunition depots, which helped reduce Russian artillery fire.

HIMARS paved the way for a stunningly successful Ukrainian counter-offensive in the Kharkiv region that began in early September and turned the balance of the war against Russia. It became apparent that HIMARS was also damaging Russian morale when Russian media published dubious stories claiming the missiles had secret capabilities, such as changing their trajectory.

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

“It took Ukraine more than two months to retake the entire right bank of the Kherson after it began its offensive,” Michael Kofman, director of CNA’s Russia Studies Program, and Rob Lee, senior fellow in the Foreign Policy Institute’s Eurasia Program, wrote at the end of December.

“Kherson finds that the overall performance of HIMARS may have been overestimated, and its performance leveled off after the first two months of battlefield use,” Kofman and Lee wrote.

Russian forces were able to withstand the artillery fire and eventually withdraw from Kherson with most of their equipment despite the threat from Ukrainian precision weapons, such as HIMARS and specially designed artillery shells.

Adjustments Russia has made in response to HIMARS “include moving logistics hubs out of range, fortifying command posts, and introducing decoys to make targeting more difficult,” Kofman and Lee wrote.

Tactically, the Russian forces in Kherson were in a difficult position: they held a bridgehead on the west bank of the Dnieper River, with only a few vulnerable ferries and a passable dam to transport supplies and reinforcements from the main Russian positions on the east bank.

Despite Ukraine deploying an impressive array of capabilities — from HIMARS and tanks to drones and special operations forces — its offensive has still met with fierce resistance.

“The fighting was fierce, with high attrition rates on both sides,” according to Kofman and Lee. “Kherson offers a cautionary tale about the challenge of offensive maneuver against an entrenched adversary with sufficient artillery and anti-aircraft defenses.”

All of this begs the question: Was HIMARS that good or was Russia that bad? For example, the Russian military relies on a highly centralized logistics network that depends on several rail lines rather than more flexible truck transport to supply troops.

At the same time, Russian doctrine calls for massive artillery barrages. This led to the large ammunition bins being placed near the front for convenience. It also meant that those huge stocks of artillery shells were within range of HIMARS missiles which – guided by GPS coordinates delivered by drones or satellites – could hit precision targets 50 miles away.

“The requirements for a large volume of fire were incompatible with adaptation to long-range precision strikes,” Kofman told Insider.

Russia took no precautions and was slow to adapt to Western missiles and long-range artillery delivered to Ukraine. However, Russia eventually adapted.

This raises another question: If much of HIMARS’ success is the result of Russian mistakes, how effective will these missiles be against other adversaries in other potential conflicts, such as a Chinese invasion of Taiwan?

For example, Ukrainian gunners enjoyed targeting data from US satellites that Russia could not attack for fear of escalating war. Ukraine had access to US intelligence, surveillance and reconnaissance “which played an important role, but because of the political parameters were untouchable for Russia,” Kofman said. “That’s why you can’t easily transfer the findings to a war with direct US involvement.”

Any military capability is most effective when deployed 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 has a master’s degree in political science. Follow him further Twitter and LinkedIn.