WASHINGTON -- President Joe Biden said Vladimir Putin would face a "consequential" U.S. response if the Russian president used nuclear or chemical weapons in the war in Ukraine.
"Don't. Don't. Don't," Biden said in an excerpt from an interview with CBS's "60 Minutes" when asked what he would say if Putin were considering using tactical nuclear weapons or chemical weapons in the monthslong conflict. "You will change the face of war unlike anything since World War II."
Biden declined to specify the possible consequences, saying that "the extent of what they do" would determine the response.
"Of course, I'm not going to tell you. It'll be consequential," Biden said. "They'll become more of a pariah in the world than they ever have been. And depending on the extent of what they do will determine what response would occur."
Biden's full CBS interview will be broadcast tonight.
Various Russian officials have issued veiled threats of nuclear escalation over Ukraine, including Foreign Minister Sergei Lavrov, who said in April there's a "serious" risk of nuclear war. Days after invading Ukraine, Putin ordered his country's nuclear forces on high alert for the first time since the end of the Cold War.
More recently, Defense Minister Sergei Shoigu told a security conference in Moscow on Aug. 16 that Russia had no plans to use tactical nuclear or chemical weapons in Ukraine.
ZELENSKYY ASKS FOR MORE
Flush with success in northeast Ukraine, President Volodymyr Zelenskyy is pressing Biden for a new and more powerful weapon: a missile system with a range of 190 miles, which could reach far into Russian territory.
Zelenskyy insists to U.S. officials that he has no intention of striking Russian cities or aiming at civilian targets, even though President Vladimir Putin's forces have hit apartment blocks, theaters and hospitals in Ukraine throughout the war. The weapon, Zelenskyy says, is critical to launching a wider counteroffensive, perhaps early next year.
Biden is resisting, in part because he is convinced that over the past seven months, he has successfully signaled to Putin that he does not want a broader war with the Russians -- he just wants them to get out of Ukraine.
A shipment of long-range guided missiles, which could also give Ukraine new options for striking Crimea, the territory Russia annexed in 2014, would likely be seen by Moscow as a major provocation, Biden has concluded.
"We're trying to avoid World War III," Biden often reminds his aides, echoing a statement he has made publicly as well.
Senior aides to the president also say that when Biden asked the Pentagon in recent weeks how much the longer-range missile systems would help Ukrainian forces during the next stage of the war, he was told the benefits would be minimal. That led him to conclude, they said, that it was not worth the risk.
The argument over the Army Tactical Missile System comes as officials in the White House, the State Department, the Pentagon and U.S. intelligence agencies appear more concerned than ever that Putin could escalate the war to compensate for his humiliating retreat.
Many of the options they are preparing for are bleak: more indiscriminate bombardment of Ukrainian cities, a campaign to kill senior Ukrainian leaders or an attack on supply hubs outside Ukraine -- in NATO countries like Poland and Romania -- that are channeling extraordinary quantities of arms, ammunition and military equipment into the country.
This account of the administration's effort to control escalation in the war is based on conversations with more than a dozen senior U.S. officials as they struggle to calibrate the next steps -- hoping to build on Ukraine's advances without triggering a wider conflict. It comes as the Ukrainians have gained momentum and the Russians, for now, are still in disarray.
U.S. officials believe they have, so far, succeeded at increasing their military, intelligence and economic assistance to Ukraine step by step, without provoking Moscow into large-scale retaliation with any major single move.
They say Putin almost certainly would have pushed back hard if Washington had, at the outset of the war, provided Ukraine with the kind of support it is getting now, such as intelligence that has allowed Ukraine to kill Russian generals and target arms depots, tanks and Russian air defenses with precision-guided rocket attacks.
Instead, the Americans believe their incremental strategy, and refusal to give Ukraine advanced weapons or aircraft that could reach deep into Russia, has put guardrails on the conflict. But Putin has grown increasingly frustrated as his military struggles.
Colin Kahl, undersecretary of defense for policy, said Friday in a statement to The New York Times, "Ukraine's success on the battlefield could cause Russia to feel backed into a corner, and that is something we must remain mindful of."
While the United States is committed to providing Ukraine with the equipment it needs to counter Russian aggression, he said the Pentagon has assessed that Ukraine does not need the Army Tactical Missile System for "targets that are directly relevant to the current fight."
FEAR OF ESCALATION
On Capitol Hill, Democrats and Republicans have expressed support for preventing the war in Ukraine from spilling into a wider conflict. But many lawmakers said the Biden administration was being overly cautious in denying Ukraine additional advanced weaponry.
Rep. Jason Crow, D-Colo., who serves on the House Intelligence and Armed Services committees, said the United States should send tactical missile systems to Ukraine.
"Sure, escalation remains a concern, and we have to be mindful of that threat," said Crow, a former Army Ranger. "But I don't think providing ATACMS is substantively escalatory. We need to provide what Ukraine needs to win."
An increased flow of arms and advice now, some former officials said, is vital to help the Ukrainians capitalize on the counteroffensive and survive the coming winter.
"We have a window of opportunity," Evelyn Farkas, a former senior defense official during the Obama administration said at a summit in Washington. "I worry that if we don't provide the Ukrainians with the weapons they need to push back further, get more territory, they will not be strong enough at the negotiating table and the Russians may regroup."
Some U.S. officials express concern that the most dangerous moments are yet to come, even as Putin has avoided escalating the war in ways that have, at times, baffled Western officials.
He has made only limited attempts to destroy critical infrastructure or to target Ukrainian government buildings. He has not attacked the supply hubs outside Ukraine.
While he has directed low-level cyberattacks against Ukrainian targets every week, they have been relatively unsophisticated, especially when compared with capabilities that Russia has shown it has, including in the SolarWinds attack on U.S. government and commercial systems that was discovered just before Biden took office.
Some officials have expressed concern that Putin could detonate a tactical nuclear weapon -- perhaps in a demonstration blast over the Black Sea or Arctic Ocean, or in Ukrainian territory. But there is no evidence that he is moving those weapons, officials say, or preparing such a strike.
One senior intelligence official said there was a debate underway inside U.S. intelligence agencies over whether Putin believes such a step would risk Russia's alienation from the countries it needs most -- especially China -- or whether he is holding the option in reserve.
Putin, despite his early setbacks, appeared generally satisfied with how the war was going in recent months, content to give his army the time to make slow progress as it pummeled Ukrainian lines with a brutal artillery campaign. But as he made clear Friday, he is content no more.
U.S. officials say Moscow is even more ready to blame the United States for its troubles than it was earlier in the war.
"The disclosures that the U.S. intelligence is helping the Ukrainian side has shifted the Russian narrative even more to the message: We are fighting NATO now," said Larissa Doroshenko, a researcher at Northeastern University.
There also are signs that Putin could be worried about his own political standing.
Public criticism in Russia is on the rise after the counteroffensive. Commentators have mostly avoided any direct critique of Putin. But some academic experts see harsh assessments of the Russian military command as an implicit criticism of Putin.
The troubles facing Putin -- from mounting criticism to the Ukrainian military strength -- mean that his escalation calculus could change.
Throughout the war, U.S. intelligence has proved adept at learning Russian military plans, but its track record on Putin's intentions is more mixed.
Intelligence officials have said publicly that Putin's war aims remain the same from the beginning of the war -- which include the removal of Zelenskyy.
In response to the recent setbacks, military experts said Putin could call up more reservists, or men who have previously served in the military -- which would be less politically fraught and could bring forces to the battlefield quicker.
What Putin decides to do could depend on his assessment of his own strength at home, how quickly he thinks Ukraine can regroup and attempt another counteroffensive -- and what he can do to deter further American support.
Information for this article was contributed by Tony Czuczka of Bloomberg News (TNS) and by David E. Sanger, Anton Troianovski, Julian E. Barnes and Eric Schmitt of The New York Times.