By Julian E. Barnes, Helene Cooper and Eric Schmitt

WASHINGTON — The United States has provided intelligence about Russian units that has allowed Ukrainians to target and kill many of the Russian generals who have died in action in the Ukraine war, according to senior US officials.

Ukrainian officials said they have killed approximately 12 generals on the front lines, a number that has astonished military analysts.

The targeting help is part of a classified effort by the Biden administration to provide real-time battlefield intelligence to Ukraine. That intelligence also includes anticipated Russian troop movements gleaned from recent US assessments of Moscow’s secret battle plan for the fighting in the Donbas region of eastern Ukraine, the officials said. Officials declined to specify how many generals had been killed as a result of US assistance.

The United States has focused on providing the location and other details about the Russian military’s mobile headquarters, which relocate frequently. Ukrainian officials have combined that geographic information with their own intelligence — including intercepted communications that alert the Ukrainian military to the presence of senior Russian officers — to conduct artillery strikes and other attacks that have killed Russian officers.

The intelligence sharing is part of a stepped-up flow in US assistance that includes heavier weapons and tens of billions of dollars in aid, demonstrating how quickly the early US restraints on support for Ukraine have shifted as the war enters a new stage that could play out over months.

US intelligence support to the Ukrainians has had a decisive effect on the battlefield, confirming targets identified by the Ukrainian military and pointing it to new targets. The flow of actionable intelligence on the movement of Russian troops that America has given Ukraine has few precedents.

Since failing to advance on Kyiv, the capital, in the early part of the war, Russia has tried to regroup, with a more concentrated push in eastern Ukraine that so far has moved slowly and unevenly.

Officials interviewed for this article spoke on the condition of anonymity to discuss details of the classified intelligence being shared with Ukraine.

The administration has sought to keep much of the battlefield intelligence secret, out of fear it will be seen as an escalation and provoke President Vladimir Putin of Russia into a wider war. US officials would not describe how they have acquired information on Russian troop headquarters, for fear of endangering their methods of collection. But throughout the war, the US intelligence agencies have used a variety of sources, including classified and commercial satellites, to trace Russian troop movements.

Defence Secretary Lloyd Austin went so far as to say last month that “we want to see Russia weakened to the degree it cannot do the kinds of things that it has done in invading Ukraine.”

Asked about the intelligence being provided to the Ukrainians, John Kirby, the Pentagon spokesperson, said that “we will not speak to the details of that information.” But he acknowledged that the U.S. provides “Ukraine with information and intelligence that they can use to defend themselves.”

After this article was first published, Adrienne Watson, a National Security Council spokesperson, said in a statement that the battlefield intelligence was not provided to the Ukrainians “with the intent to kill Russian generals.”

Not all the strikes have been carried out with US intelligence. A strike over the weekend at a location in eastern Ukraine where Gen. Valery Gerasimov, Russia’s highest-ranking uniformed officer, had visited was not aided by US intelligence, according to multiple US officials. The United States prohibits itself from providing intelligence about the most senior Russian leaders, officials said.

But US intelligence was critical in the deaths of other generals, officials acknowledged.

The United States routinely provides information about the movement of Russian troops and equipment, and helps Ukraine confirm the location of critical targets. Other NATO allies also give real-time intelligence to the Ukrainian military.

The Biden administration is also supplying new weaponry that should improve Ukraine’s ability to target senior Russian officers. The smaller version of the Switchblade drone, which is now arriving on the battlefield, can be used to identify and kill individual soldiers, and could take out a general sitting in a vehicle or giving orders on a front line.

US officials have acknowledged publicly that the United States began giving Ukraine actionable intelligence in the run-up to Russia’s invasion on Feb. 24. Before the invasion, for example, US intelligence agencies warned of an impending attack on the Hostomel airport north of Kyiv. That allowed Ukraine to strengthen its defences. Russian airborne forces were ultimately unable to hold the airfield.

While the information the United States has provided Ukraine has proved valuable, Russian generals have often left themselves exposed to electronic eavesdropping by speaking over unsecure phones and radios, current and former US military officials said.

“It shows poor discipline, lack of experience, arrogance and failure to appreciate Ukrainian capabilities,” said Frederick B. Hodges, the former top US Army commander in Europe who is now with the Centre for European Policy Analysis. “It is not hard to geo-locate someone on a phone talking in the clear.”

Russian military tactics have also left senior generals vulnerable. A centralized, top-down command hierarchy gives decision-making authority only to the highest levels — compared to the more decentralized American structure that pushes many battlefield decisions to senior enlisted personnel and junior officers — forcing Russian generals to make risky trips to the front lines to resolve logistical and operational issues.

“When there are problems, the general officers have to go sort it out,” Hodges said.

Although the administration remains wary of inflaming Putin to the point that he further escalates his attacks — President Joe Biden has said he will not send US troops to Ukraine or establish a “no-fly zone” there — current and former officials said the White House finds some value in warning Russia that Ukraine has the weight of the United States and NATO behind it.

Some European officials believe, despite Putin’s rhetoric that Russia is battling NATO and the West, he has so far been deterred from starting a wider war. U.S. officials are less certain, and have been debating for weeks why Putin has not done more to escalate the conflict.

Officials said Moscow has its own calculations to weigh, including whether it can handle a bigger war, particularly one that would allow NATO to invoke its mutual defence charter or enter the war more directly.

“Clearly, we want the Russians to know on some level that we are helping the Ukrainians to this extent, and we will continue to do so,” said Evelyn Farkas, the former top Defence Department official for Russia and Ukraine in the Obama administration. “We will give them everything they need to win, and we’re not afraid of Vladimir Putin’s reaction to that. We won’t be self-deterred.”

But intelligence sharing is considered a safe form of help because it is invisible, or, at least, deniable.

US intelligence has given secret information to Ukraine in a wide range of areas, from Russian troop movements to targeting data, officials said.

Last month, the United States increased the flow of intelligence to Ukraine about Russian forces in the Donbas and Crimea, as Kyiv’s military forces prepared to defend against a renewed offensive by Moscow in eastern Ukraine, US officials said.

“There’s a significant amount of intelligence flowing to Ukraine from the United States,” Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, told a Senate panel on Tuesday (3). “We have opened up the pipes.”

-New York Times