In late June, Ukraine announced it had destroyed a Russian military base in Izyum, in the eastern Donbas region, killing at least 40 soldiers. Another strike that night reportedly killed a commander of Russia's elite VDV paratrooper regiment. 

They were the first Russian victims of HIMARS (the M142 High Mobility Artillery Rocket System), a mid to long-range missile system that has allowed Ukraine to strike deep beyond the front lines for the first time since Russia invaded in February.

The US began to send HIMARS to Ukraine in June, as Russia continued to advance through Donbas and Luhansk in an artillery-heavy offensive. Since then, HIMARS have become a valuable tool for Ukraine's military, which says it has conducted dozens of strikes on Russian targets, including air defense systems and ammunition stores.

On Wednesday, US Secretary of Defense Lloyd Austin said the US would deliver four more HIMARS, bringing the total number sent to Ukraine up to 16. 

"HIMARS have already made a HUUUGE difference on the battlefield," Ukraine's defense minister, Oleksii Reznikov, tweeted on July 9. "More of them as well as [US] ammo & equipment will increase our strength and help to demilitarize the terrorist state."

What is the HIMARS?

The HIMARS is a truck-mounted multiple rocket launcher manufactured by Lockheed Martin. It entered production in the 1990s and was first deployed by the US military in the mid-2000s.

The launcher can be mounted with either six GPS-guided, mid-range GMLRS, which are guided missiles with a range of 92 kilometers (57 miles) or one long-range guided ATACMS surface-to-surface missile, with a range of 300 kilometers (186 miles). However, the US has not supplied ATACMS to Ukraine, fearing they would be used to attack Russian soil, which would be seen by the Kremlin as an escalation of American involvement in the conflict.

The HIMARS is manned by three crew members and takes five minutes to reload. A mobile system, it can relocate quickly after launch to protect the crew and system from any return fire from an enemy combatant, an ability called "shoot and scoot." 

The system costs around $5 million (€4.8 million) per unit to produce and more than 540 have been used in the field, according to Lockheed Martin. The US, Romania, Singapore, Untied Arab Emirates, Jordan and now Ukraine are the only countries to currently possess HIMARS. Sales have been approved to Poland and Taiwan, and last week Estonia confirmed it would purchase up to six systems from the US as part of a $500-million package.

HIMARS have been deployed previously in Afghanistan, where the US used them against the Taliban in Kandahar province, and against so-called "Islamic State" forces in Iraq during the battle of Mosul.

Are the HIMARS a game-changer?

In the early days of Russia’s invasion of Ukraine, foreign-supplied anti-tank weapons, like the NLAW and Javelin, proved crucial in defending the advance of Russian armored columns toward cities such as Kyiv and Kharkiv.

In recent months, Russia has been trudging slowly through eastern Ukraine, capturing the remaining Ukrainian-held cities in Luhansk and much of Donbas under a hail of heavy artillery fire. 

Ukraine is outgunned when it comes to conventional artillery, which has a maximum range of around 40 kilometers (25 miles). But the HIMARS have proven crucial in upping Ukraine's military strength — effective at striking key command, communications and logistics centers well behind enemy lines, all while remaining safely out of range of Russian shelling.

Their impact has clearly been felt by Russia, which does not appear to have an easy way to defend its troops and infrastructure from these precision missiles. On Monday, Russian Defense Minister Sergei Shoigu gave orders to "prioritize the defeat of the enemy's long-range missile and artillery weapons with high-precision weapons," according to a state Telegram channel.

Ukraine has used HIMARS to interrupt Russia's supply of artillery to its front, where Russian forces are using an estimated 20,000 shells per day, according to a report by the Royal United Services Institute. In early July, videos posted to social media showed what appeared to be ammunition dumps in flames, including a truck center in Donetsk belonging to the Russia vehicle manufacturer Kamaz; the structures were likely struck by HIMARS.

Precision rockets have also been used to hit high-value targets. According to Serhiy Bratchuk, an official for the Odessa region, a HIMARS rocket strike earlier this month near Kherson killed Russian Major General Artyom Nasbulin, the chief of staff of the 22nd Army Corps.

The Russian S-400 air defense missile system has apparently been unable to intercept these missiles, and it remains unclear whether Russian intelligence has managed to successfully locate and attack them. The Russian Defense Ministry said on Friday it had destroyed four HIMARS. However, General Mark Milley, chairman of the US Joint Chiefs of Staff, said in a press conference on Wednesday that none of the systems have so far been destroyed. He also said that around 200 Ukrainian troops have been trained to use HIMARS.

As with other weapons that appeared to briefly turn the tide of the war, like NLAWs and Turkish Bayraktar drones, Russia may find ways to adapt to or reduce the effectiveness of HIMARS. 

There are also concerns that the systems will be difficult to maintain and repair over time, and that stocks of the costly missiles will deplete quickly.

"The issue will become ammunition and the consumption rates," said Milley. 

Edited by: Cristina Burack