Ukrainian President Volodymyr Zelensky told German media on Wednesday he does not believe Russia will use nuclear weapons, after President Vladimir Putin said Moscow would use all means to protect its territory.

"I don't believe that he will use these weapons," Zelensky told the TV station of Germany's Bild newspaper, referring to nuclear arms. "I don't believe that the world will allow him to use these weapons."

The Ukrainian leader warned against giving in to Putin's threats.

"Tomorrow, Putin can say — as well as Ukraine, we want part of Poland, otherwise we will use atomic weapons. We cannot make these compromises," he said.

The Russian president's decision to order a partial mobilisation was because of the low morale among his forces, said Zelensky.

"He needs an army of millions… he sees that a large part of those (troops) who come to us, just run away," he said.

Putin "wants to drown Ukraine in blood, also the blood of his own soldiers", Zelensky said.

Putin announced early Wednesday the mobilisation, as Ukraine mounts a lightning counter-offensive and seizes back swathes of territory, and also hinted that Moscow could use atomic arms over the conflict.

Annexation referendums set to be held in Russian-occupied areas of Ukraine were "sham referendums", Zelensky said, adding 90 percent of states would not recognise them.

The Ukrainian leader said his nation's forces would push on with their military campaign and "free our territory".

He reiterated that Kyiv wants Germany to send battle tanks to aid Ukraine in the fight against Russia, heaping fresh pressure on Chancellor Olaf Scholz's government.

While Berlin has sent some armaments to Ukraine, they have so far refused to transfer the tanks that Kyiv is urgently appealing for.

"Give us these weapons," Zelensky said. "Battle tanks mean that more people's lives can be saved."

He criticised the German government's position that it does not want to "go it alone", as no other ally has transferred Western-made battle tanks to Ukraine.

"You are an independent state… don't say 'First the US, then Poland, and so on'."

Zelensky also said he believes Putin has "already lost the war".

"From the first day of the invasion of Ukraine's territory, he had lost this war. No one will forgive him."

US says taking Putin's 'irresponsible' nuclear threat 'seriously'
Washington (AFP) Sept 21, 2022 – The United States is taking Russian President Vladimir Putin's "irresponsible" veiled threat to use nuclear weapons "seriously," a senior US official said Wednesday.

"It's irresponsible rhetoric for a nuclear power to talk that way. But it's not atypical for how he's been talking the last seven months and we take it very seriously," John Kirby, spokesman for the White House's National Security Council, told ABC's "Good Morning America" after Putin said he would use "all available means" to protect Russian territory.

"We're monitoring as best we can — their strategic posture. So if we have to, we can alter ours. We've seen no indication that that's required right now."

Kirby reiterated previous comments by President Joe Biden when asked what the US response would be to Russia reaching for its nuclear arsenal, which analysts speculate could mean detonating a demonstration blast over the Black Sea, using battlefield nuclear warheads to limit the radiation, or ultimately using a larger weapon.

"There'll be severe consequences. Not only will he be that much more of pariah on the world stage, but there'll have to be severe consequences that the international community will have."

Kirby described Putin's order to mobilize an expected 300,000 reservists from around Russia as a sign of weakness.

"It's definitely a sign that he is struggling," Kirby said. "He has suffered tens of thousands of casualties. He has terrible morale, unit cohesion on the battlefield. Command and control has still not been solved. He's got desertion problems and he's forcing the wounded back ingo the fight — so clearly manpower is a problem."

Kirby said "sham" referendums on joining Russia that are being prepared in Russian-invaded areas of Ukraine would not change US policy.

"That is Ukrainian territory. It doesn't matter what sham referendum they put in place," Kirby said. "We're going to continue to support Ukraine with security assistance and other financial aid, as the president said, for as long as it takes."