The message to NATO from President Vladimir Putin was simple and stark: Don't go too far in providing military support for Ukraine, or you'll risk a conflict with Russia that could quickly turn nuclear.
As the war in Ukraine turns slowly in Moscow's favor, Putin declared he doesn't need nuclear weapons to achieve his goals. But he also says it's wrong for the West to assume that Russia will never use them.
"It mustn't be treated in a light, superficial way," Putin said in June, reaffirming that Russia's nuclear doctrine calls for using atomic weapons if it perceives a threat to its sovereignty and territorial integrity.
Moscow's nuclear messaging — coming as NATO allies move to shore up exhausted and outgunned Ukrainian forces — heralds what could become the most dangerous phase in the war.
Drills, threats and signals
Moscow has carried out drills with its tactical — or battlefield — nuclear weapons in southern Russia and with ally Belarus, where some were deployed in 2023. Russian Defense Ministry videos showed Iskander missile launchers, nuclear-capable warplanes and sea-launched missiles.
The Kremlin described the exercises as a response to the West pondering the deployment of NATO troops to Ukraine and allowing Kyiv to use longer-range weapons for limited strikes on Russian territory.
FILE - Soldiers stand next to a Russian RS-24 Yars ballistic missile parked along Tverskaya street prior to a rehearsal for the Victory Day military parade in Moscow, May 2, 2024.
"Reliance on nuclear threats and signals is an enduring trend in Russia's activities amid the war in Ukraine," said Heather Williams, senior fellow at the Washington-based Center for Strategic and International Studies. "Russian leadership may be assuming it has more at stake in Ukraine than NATO, and nuclear threats are one means of signaling its commitment to winning the war in the hopes of scaring off Western intervention."
Ever since launching the Feb. 24, 2022, invasion, Putin has repeatedly referred to Russia's nuclear might to discourage Western intervention. The United States and NATO criticized the nuclear saber-rattling but said they haven't seen any changes in Russia's nuclear posture warranting a response.
After early setbacks in Ukraine, Putin said Moscow was prepared to use "all means" to protect Russian territory, fueling fears he could turn to tactical nuclear weapons to halt Kyiv's advances. Putin later toned down his rhetoric after Ukraine's 2023 counteroffensive didn't achieve its goals.
Amid Russia's recent military successes, Putin said Moscow doesn't need nuclear weapons to win in Ukraine. Simultaneously, however, he warned that Kyiv's strikes on Russian soil with Western-supplied longer-range weapons would mark a major escalation because they would involve Western intelligence and military personnel — something the West denies.
"Representatives of NATO members, particularly in small countries of Europe, should be aware of what they are playing with," he said, adding they could be mistaken to rely on U.S. protection if Russia strikes them.
"The constant escalation could lead to grave consequences," he said. "If those grave consequences come to Europe, how will the U.S. act in view of our parity in strategic weapons? Hard to say. Do they want a global conflict?"
FILE - Photo taken from video released by the Russian Defense Ministry, July 1, 2024, Russian soldiers fire from the BM-21 'Grad' self-propelled 122mm multiple rocket launcher in undisclosed location.
Aiming the 'nuclear pistol'
In May, Russian radar facilities were attacked by Ukrainian drones. One damaged a radar in the southern Krasnodar region, according to satellite images. Another targeted a similar facility in the southern Urals, about 1,500 kilometers (930 miles) east of the border.
Both are part of Russia's early warning system to spot intercontinental ballistic missile launches thousands of kilometers (miles) away. Moscow and Washington rely on such systems to track each other's launches.
Along with earlier Ukrainian raids on Russian nuclear-capable bomber bases, the radar strikes could qualify as triggers for atomic-weapons use under Moscow's nuclear doctrine. Russian hawks urged the Kremlin to respond forcefully.
At a June forum in St. Petersburg, Kremlin-connected foreign policy expert Sergei Karaganov urged Putin to "aim a nuclear pistol at our Western adversaries" to achieve victory in Ukraine.
Putin responded cautiously, saying he saw no security threats that warranted using Russia's nuclear arsenal. At the same time, he indicated Moscow was pondering changes in its nuclear doctrine.
FILE - In this photo released by the Russian Defense Ministry on Feb. 2, 2024, Russian troops load an Iskander missile onto a mobile launcher during drills at an undisclosed location in Russia.
Amending the nuclear doctrine
Since the war began, hawks have urged a revision of the doctrine, which says Moscow could use nuclear weapons in response to a nuclear strike or an attack with conventional weapons that threatens "the very existence" of the Russian state. Some of them argue the threshold is too high, leaving the West with the impression that the Kremlin won't ever touch its nuclear arsenal.
Foreign affairs analyst Dmitri Trenin of the Institute of World Economy and International Relations, a Moscow think tank advising the Kremlin, urged modifying the doctrine to declare that Russia could use nuclear weapons first when "the core national interests are at stake," like in Ukraine.
"It's important to persuade the ruling elites in the U.S. and in the West as a whole that they won't be able to stay comfortable and fully protected after provoking conflict with Russia," Trenin said.