Senior Russian military leaders recently had conversations to discuss when and how Moscow might use a tactical nuclear weapon in Ukraine, contributing to heightened concern in Washington and allied capitals, according to multiple senior American officials.

President Vladimir V. Putin was not a part of the conversations, which were held against the backdrop of Russia’s intensifying nuclear rhetoric and battlefield setbacks.

But the fact that senior Russian military leaders were even having the discussions alarmed the Biden administration because it showed how frustrated Russian generals were about their failures on the ground, and suggests that Putin’s veiled threats to use nuclear weapons might not just be words.

Still, American officials said they had seen no evidence that the Russians were moving nuclear weapons into place or taking other tactical measures to prepare for a strike.

The intelligence about the conversations was circulated inside the US government in mid-October.

US officials would not describe the scenarios the military leaders considered for use of a nuclear weapon.

However, William J. Burns, the CIA director, has previously said that Putin’s “potential desperation” to extract a victory in Ukraine and setbacks in the war could lead Russia to use one.

John F. Kirby, a National Security Council official, declined to comment on “the particulars of this reporting”.

“We’ve been clear from the outset that Russia’s comments about the potential use of nuclear weapons are deeply concerning, and we take them seriously,” Kirby said. “We continue to monitor this as best we can, and we see no indications that Russia is making preparations for such use.”

The Pentagon estimates that Russia has a stockpile of as many as 2,000 tactical nuclear weapons, which are designed to be used on battlefields to overwhelm conventional forces.

No tactical nuclear weapon has ever been used in combat, but one could be deployed in any number of ways, including by missile or artillery shell.

Tactical nuclear weapons carry lower yields and are meant to be used at shorter ranges than the warheads carried on intercontinental ballistic missiles.

Military experts say the use of a nuclear weapon —for the first time in more than75 years — would fundamentally change the shape of the war.

Putin has sole authority over whether to use a tactical device and would make the decision to deploy one regardless of the views of his generals.

New York Times News Service