Advanced U.S. Arms Make a Mark in Ukraine War, Officials Say

WASHINGTON — The most advanced weapons that the United States has so far supplied Ukraine are making an impact in their first several days on the battlefield, destroying Russian ammunition depots and command centers, American and Ukrainian officials say.

Ukraine’s military had eagerly awaited the arrival of the first batch of truck-mounted, multiple-rocket launchers, whose satellite-guided rockets have a range of more than 40 miles, greater than anything Ukraine had possessed. The weapons have even won grudging respect from some Russians for their accuracy and power, analysts said.

Still, only four of the launchers, called High Mobility Artillery Rocket Systems or HIMARS, and their U.S.-trained crews are in the fight, though four more are expected this month. Ukrainian officials say they need as many as 300 multiple-rocket launchers to combat Russia, which is firing several times as many rounds as Ukraine’s forces in the artillery-driven war of attrition in the country’s east.

Ukrainian soldiers are using their new weapon judiciously, firing one or two guided rockets at ammunition depots or command posts, often at night, and keeping them well away from the front lines to protect them, Pentagon officials and military analysts say.

“So far they seem to be a quite useful addition,” Rob Lee, a Russian military specialist at the Foreign Policy Research Institute in Philadelphia and a former U.S. Marine officer, said of the systems. “They will help hinder further Russian advances, but they won’t necessarily mean Ukraine will be able to take back territory.”

The HIMARS are the centerpiece of a raft of new Western long-range weapons that the outgunned Ukrainian military is switching over to as its arsenal of Soviet-era howitzer and rocket ammunition dwindles.

The Western weapons are more accurate and highly mobile, but it takes weeks to deploy them from the United States and Europe and to train soldiers to use them. In the meantime, Russia’s military is making slow but methodical gains in the eastern region of Donbas, where both sides have taken heavy losses.

The Biden administration says that all eight HIMARS should be in Ukraine by mid-July. The first group of 60 Ukrainian soldiers trained to use them are now firing the guided rockets in battle, and a second group is undergoing training in Germany. Britain and Germany have each pledged three similar multiple-rocket launchers.

A senior Pentagon official said this week that the Ukrainians appear to be employing the HIMARS with deadly effectiveness and that the four additional systems would be deployed in “the near future.”

At a NATO summit in Madrid on Thursday, President Biden promised $800 million more in security assistance to Ukraine, including more ammunition for the HIMARS. The United States has committed nearly $7 billion in military aid since the war started in February.

Since Russia focused its campaign on the east after failing to seize Kyiv, Ukraine’s capital, and other cities in the north, Ukrainian officials have pleaded with the United States and other allies for more advanced artillery.

On June 23, Ukraine’s defense minister, Oleksiy Reznikov, announced that the first American HIMARS had arrived, promising in a Twitter message, “Summer will be hot for russian occupiers. And the last one for some of them.”

Two days later, Gen. Valeriy Zaluzhnyi, the top commander of Ukrainian forces, posted a video on the social media site Telegram of the HIMARS in use. “Artillerymen of the Armed Forces of Ukraine skillfully hit certain targets — the enemyʼs military facilities on our Ukrainian territory,” he said.

American officials said the Ukrainian statements were accurate, and Mr. Lee added that even Russian accounts acknowledged the HIMARS to be early successes.

“In general, it seems they respect them and realize they’re quite capable,” said Mr. Lee, citing a popular Russian Telegram channel whose posts are shared by Russian defense accounts.

There is still a debate as to how many multiple-rocket launchers Ukraine needs.

Mykhailo Podolyak, an adviser to President Volodymyr Zelensky of Ukraine, said in June that Ukraine needed 300 multiple-launch rocket systems and 500 tanks, among other things, to achieve battlefield parity — several times as much heavy weaponry as has been promised.

Michael G. Vickers, the Pentagon’s former top civilian official for counterinsurgency strategy, said the Ukrainians needed at least 60, and perhaps as many as 100, HIMARS or other multiple-launch rocket systems to win the artillery battle.

“There are plenty available that could be supplied at minimal strategic risk,” said Mr. Vickers, who was the principal C.I.A. strategist for arming anti-Soviet forces in Afghanistan in the mid-1980s.

Mr. Lee noted that future success of the HIMARS and other multiple-rocket launchers depended not only on the number sent, but also on how much and what type of ammunition the United States and other allies provided.

The transition to American-made rocket weapons was forced in part by the supply problems the Ukrainian army has faced.

Ukraine has three types of Russian-made mobile rocket launchers, but ammunition for only the one with the shortest range is produced by its allies. Ammunition for Ukraine’s longer-range artillery rockets is made solely by Russia and Belarus.

For the HIMARS, Ukrainian forces rely on a guided rocket that is aided by GPS signals and accurate to within about 30 feet of its intended target. Before launch, a three-person crew inputs coordinates for each strike.

After a NATO meeting in Brussels on June 15, Defense Secretary Lloyd J. Austin III said that the guided rockets, fired by both the new American-provided launchers that can carry one pack of six rockets and the launchers from Britain and Germany that can carry twice that, were far more capable than Russian-made artillery rocket weapons that have been used on the battlefield.

“These are precision munitions, and with a properly trained crew they will hit what they’re aiming at,” Mr. Austin said. “Over time, we think the combination of what the allies and partners can bring to the table, it will make a difference.”

Besides firing long-range guided munitions, the wheeled HIMARS trucks have the advantage of speed. Not only can they drive quickly to a firing point, they can program targets while en route, launch their rockets singly or in a ripple of all six within a minute, and reload far faster than anything in use by the Russians.

With 200 pounds of high explosives in each rocket, a HIMARS salvo can rival the devastating effect of an airstrike from a jet loaded with precision-guided bombs.

Following Mr. Austin’s remarks at NATO, Gen. Mark A. Milley, chairman of the Joint Chiefs of Staff, hinted at the effect HIMARS could have in Ukrainian hands.

“If they use the weapon properly,” General Milley said, “they ought to be able to take out a significant amount of targets.”