The U.S. has warned the Kremlin of the devastating consequences Russia would face should nuclear weapons be used in Ukraine, national security adviser Jake Sullivan said Sunday.
"If Russia crosses this line, there will be catastrophic consequences for Russia," Sullivan said on NBC's "Meet the Press." "The United States will respond decisively. In private channels, we have spelled out in greater detail exactly what that would mean."
Ukraine President Volodymyr Zelenskyy said he does not believe Putin was bluffing when he said last week that he would be justified in using any force necessary — implying tactical nuclear weapons are not off the table.
"He wants to scare the whole world," Zelenskyy said. "I think the world is deterring it and containing this threat. We need to keep putting pressure on him."
Sullivan also said Putin must be held accountable for the war crimes and atrocities Russian troops have committed in Ukraine, but acknowledged diplomacy will ultimately be required to end the conflict. That almost certainly won't happen until Putin's ready to negotiate.
"One man chose this war," Sullivan said. "One man is directing this war. One man is responsible for this war. That man is Vladimir Putin.''
A DRAFT AND MASS GRAVES: Last week's key events in Ukraine's war with Russia
►Pink Floyd co-founder Roger Waters canceled two concerts scheduled for April 2023 in Poland amid outrage over his online comments about the war. Waters wrote an open letter to Ukrainian first lady Olena Zelenska on Sept. 5 in which he blamed “extreme nationalists” in Ukraine for having “set your country on the path to this disastrous war.” In a follow-up posting, he also accused Washington of fueling the war.
►Russian police arrested nearly 750 people across scores of cities Saturday -- including some children -- for protesting against the war and the mobilization of civilians. Protests continued Sunday.
►Two U.S. military veterans who disappeared more than three months ago while fighting with Ukrainian forces are back in Alabama after a prisoner exchange. Alex Drueke and Andy Huynh had disappeared June 9.
►Serbian Foreign Minister Nikola Selakovic on Sunday played down an agreement signed with Russia, saying it was “technical” and not related to security issues. Serbia, seeking EU membership, has not joined in the bloc's sanctions against Russia.
ANTI-WAR PROTESTS IN RUSSIA: Fears for the drafted as 'cannon fodder' and a brutal response by police
Kremlin forcing Ukrainians to fight against their own country, reports say
Besides starting to draft hundreds of thousands of Russians to fight in Ukraine, President Vladimir Putin's government is trying to force Ukrainians to combat against their own country.
Russian forces controlling the Kherson and Zaporizhzhia regions are not allowing Ukrainian men ages 18 to 35 to leave and making them report for military duty, prompting many of them to go into hiding, the New York Times reported.
In addition, the Kremlin may be about to coerce Ukrainian prisoners of war to fight on the Russian side, in violation of the Geneva Convention, the Institute for the Study of War said in an update, citing Russian state media reports.
Putin announced a highly unpopular partial mobilization of military reservists Wednesday as he seeks to bolster his troops in Ukraine after significant casualties and the loss of major swaths of territory in the northeastern Kharkiv region.
Overwhelming support for 'sham' referendum, Russian firm says
About 93% of those casting their ballots on the first day of the referendum on the Zaporizhzhia region joining the Russian Federation were in favor, according to a poll released Sunday by a Russian firm.
The Crimean Republican Institute for Political and Sociological Research said it surveyed 500 residents of the Russian-occupied region. Ukrainian and U.S. officials have dismissed the voting for "sham referendums," which began Friday.
Zelenskyy said Sunday that Russia is pushing ahead with referendums in parts of Ukraine it controls because President Vladimir Putin knows he is losing the war and must justify continuing to fight it. Speaking on CBS's "Face the Nation," Zelenskyy said Putin plans on annexing the territories so he can justify continuing the invasion by claiming he is actually defending Russian territory.
Zelenskyy said people who fail to support annexation could face retribution – such as seeing their electricity cut off. The Russians "won't give them an opportunity to live a normal human life," he said.
A monthlong Ukraine counteroffensive has driven Russia back from thousands of miles of Ukraine territory and compelled Putin to approve a "partial" military mobilization aimed at adding 300,000 soldiers to his battered military. Zelenskyy sees that as an acknowledgement that "their army is not able to fight with Ukraine anymore.”
"Look, he knows," Zelenskyy said. "He feels it, and his military leadership reports to him. He knows that he's losing the war. In the battlefield, Ukraine has seized the initiative. He cannot explain to his society why."
EU countries split over welcoming fleeing Russians
EU nations have remained remarkably unified in their opposition to Russia's war in Ukraine despite the huge toll they're paying in sky-high energy prices. Now, another issue related to the war threatens to test their resolve.
As thousands of Russians of fighting age flee the country to escape a mobilization of civilians that aims to boost troops by 300,000, EU members are debating whether to grant them asylum.
Germany and France have expressed an interest in providing refuge, and a group of more than 40 French senators said, “Closing our frontiers would fit neither with our values nor our interests.”
But that's not a unanimous stance among the bloc's 27 members. Lithuania, Latvia and Estonia, the three Baltic countries that were once a part of the Soviet Union and share a border with Russia, have voiced opposition to opening their doors to Russian refugees.
“Russians should stay and fight. Against Putin,” Lithuanian Foreign Minister Gabrielius Landsbergis tweeted.
Finland also said it intends to “significantly restrict” entry to Russians entering the EU through its border with Russia. A Finnish opposition leader, Petteri Orpo, said fleeing Russian military reservists were an “obvious” security risk and “we must put our national security first.”
This article originally appeared on USA TODAY: Ukraine updates: Zelenskyy says Putin 'knows he is losing this war'