Some U.S. Weapons Stymied by Russian Jamming in Ukraine

Some American-made, precision-guided weapons supplied to Ukraine have proved ineffective on the battlefield, their accuracy badly diminished by Russian jamming efforts, according to Ukrainian commanders and a Ukrainian military research project.

The projectiles performed well when first introduced to the battlefield, but lost effectiveness as Russian forces adapted their defenses, two confidential Ukrainian reports found. The problem prompted the Ukrainian military to stop using the weapons, two artillery commanders said.

The reports, first revealed by The Washington Post, focus on the American-made Excalibur, a 155-millimeter guided artillery shell, and the Ground Launched Small Diameter Bomb or GLSDB. One of the reports was shown to The New York Times by people familiar with the research. The second report was described but not shown to a reporter. The individuals asked not to be identified because the reports contain classified military information.

Every war is a laboratory of sorts for weapons systems, and Ukraine has provided a testing ground for weapons that have not previously been used against such a sophisticated, high-tech enemy as Russia. The performance of U.S. weapons and Russian weapons, defensive as well as offensive, is closely monitored by the Pentagon and NATO — as well as Russia and China — with significant implications for future weaponry.

More immediately, Ukrainian commanders say, some of the Western weapons supplied to them have failed them at the cost of lives.

Russia has deployed electronic warfare systems around static targets such as headquarters and command centers that might be targets of Ukrainian precision weapons. The systems blast out so much interference that they drown out the GPS signal that guides the Excalibur’s targeting software, said Thomas Withington, an associate fellow at the London-based Royal United Services Institute and a specialist in electronic warfare.

The data in the reports corroborates comments made by Ukrainian military officials in recent months, including the former army chief Gen. Valery Zaluzhny who said that some Western projectiles had afforded Ukraine significant superiority against the Russian forces, but only for a short period of time.

General Zaluzhny named the Excalibur shell as a prime example of a Western weapon that lost effectiveness because its targeting system uses GPS, the global positioning system, which is particularly susceptible to Russian jamming.

Ukrainian officials and military analysts have described similar problems with the Joint Direct Attack Munition kit called JDAM and shells used with the High Mobility Artillery Rocket System, known as HIMARS, both of which rely on GPS.

The GLSDB, a precision munition with a longer range than the Excalibur, produced jointly by Boeing and the Swedish company Saab, has also been hampered by Russian electronic warfare, according to the second military report.

Ukrainian troops have ceased deploying the GLSDB on the battlefield, according to Andrew Zagorodnyuk, head of the Center for Defense Strategies, a research organization in Kyiv.

An official from the U.S. Department of Defense press operations office, who asked not to be named, in accordance with military protocol, said in an electronic message that America had supplied more than 7,000 precision-guided 155-millimeter rounds to Ukraine since February 2022, but added that he could not give more specific information.

“We are very aware of the electronic warfare threat that Russia poses in Ukraine and that this threat is continually evolving,” the official wrote.

“As a result, we work closely with Ukraine, along with defense industry partners, to continually assess and provide rapid solutions to these threats, and to help ensure Ukraine remains effective in a very complex EW environment. This includes the ability to deliver precision munitions on the battlefield,” the official wrote, using EW to refer to electronic warfare.

Ukraine began the research because of the seriousness of the targeting failures, but also in the spirit of collaboration as a NATO ally, the people who had knowledge of the project said. It was important, one of them said, for the Ukrainian military to give feedback to Western partners on the performance of their weapons against a sophisticated military power like Russia.

The researchers collected data on the usage of nearly 3,000 Excalibur shells that were fired from December 2022 through August 2023 by American-supplied M777 howitzers on the front lines in Kherson in the south, Kharkiv in the northeast and Bakhmut in the eastern Donetsk region.

The reporting showed that the proportion of confirmed successful strikes dropped in a period from January to August 2023 from a high of 55 percent to a low of 7 percent in July and 6 percent in August, the months when Ukraine’s struggling summer counteroffensive was at its height. At one point, only one in 19 Excalibur rounds was hitting its target, according to one of the people familiar with the report. At that rate, the report calculated, the price of a successful strike ballooned to $1.9 million in August, 2023, from $300,000 the previous January.

Commanders of Ukrainian artillery units confirmed that the Excalibur shells had proved very accurate in hitting targets when first introduced in 2022, but later had been effectively neutralized by Russian jamming.

“We have some problems with accuracy,” said a commander of an artillery unit in the 45th Brigade operating in Donetsk region, who uses the call sign Musician, in accordance with Ukrainian military protocol.

The American M777 howitzers used by Musician’s crew were praised for their capabilities when they were first introduced into the Ukrainian theater in 2022. But Musician said his unit had stopped using Excalibur shells at the beginning of 2023 because of their ineffectiveness.

Instead, he said, they were firing unguided artillery shells, which are less accurate and require greater quantities of ammunition to take out a target.

Another commander, who for security reasons gave only his first name, Oleh, said that he had sometimes received supplies of other weaponry, including laser-guided projectiles, which are less affected by Russia’s jamming of GPS signals.

It is not unusual for weapons systems to lose effectiveness during intense warfare, as determined opponents find new ways to counter them.

The most effective countermeasure to combat jamming of the GPS signal is simply to eliminate the source of the interference, military analysts said. Ukrainian forces have concentrated on knocking out fixed Russian radars and other jamming equipment, in particular in the Crimean Peninsula, which has then allowed them to hit targets like command posts and supply depots deep behind enemy lines, Mr. Withington said.

At closer range, both the Russian and Ukrainian armies employ mobile electronic jammers to deflect explosive drones, which use GPS to home in on their targets.

But Russian jamming is not impenetrable, said Michael Bohnert, an engineer at RAND who specialized in electronic warfare in the U.S. Navy. Countermeasures can include simple techniques, like changing the timing and the place from which the munitions are launched. Guidance systems that rely on lasers or maps of the terrain avoid the problem of jamming GPS. Western suppliers have also developed software patches for some projectiles to improve resistance.

“You can always find a way to get something through,” Mr. Bohnert said.

He noted that the Excalibur was designed in the 1990s, when GPS was in its infancy and electronic warfare technology was not nearly as sophisticated as it is now. “Those older ones fundamentally have difficulties,” he said. “Better weapons should have been given earlier.”

Daniel Patt, a senior fellow at the Hudson Institute, a Washington-based research organization, warned that the experience with the Excalibur in Ukraine was an example of how superior weapons systems can be handicapped by a lack of software adaptability and urged the Department of Defense to foster a culture of innovation and agility to be able to adapt quickly.

“The life cycle of a radio in Ukraine is only about three months before it needs to be reprogrammed or swapped out as the Russians optimize their electronic warfare against it,” Mr. Patt wrote in his testimony. “The peak efficiency of a new weapon system is only about two weeks before countermeasures emerge.”