Australians should prepare for the war in Ukraine to go on for longer than expected, the federal government says.
Defence Minister Richard Marles says Australia would stand with Ukraine for the long run.
"It has all the potential for it to be a protracted conflict," he told Sky News on Sunday.
"We need to prepare ourselves for this turning into a protracted conflict."
'Appalling' nuclear comments from Putin
Russian officials have repeated Russian President Vladimir Putin's veiled threat to use nuclear force against any menace to Russia's "territorial integrity".
Addressing the UN General Assembly over the weekend, Russian Foreign Minister Sergei Lavrov outlined the cases in which use of the destructive weapons is acceptable.
"We have a doctrine for nuclear security which is an open document," he said.
Mr Marles branded the threats as "appalling".
"Comments we've seen from Vladimir Putin in the last few days, which speak to the behaviour of Russia, cannot be allowed," Mr Marles told Sky News on Sunday.
"The mobilisation of the 300,000 reservists in Russia is a step in completely the wrong direction.
"Russia needs to stop and Russia needs to leave Ukraine."
The foreign ministers of China and India urged Russia to act to in Ukraine in their speeches to the UN General Assembly.
Diplomats in Europe have also shared their concern over the nuclear threat, with EU foreign policy chief Josep Borrell telling the BBC it must be taken seriously.
"Certainly it's a dangerous moment because the Russian army has been pushed into a corner, and Putin's reaction - threatening using nuclear arms - it's very bad."
Ukraine request for more military aid progressing: Marles
Mr Marles said Australia is working through Ukraine's request for more Bushmaster vehicles, Hawkei protected light vehicles and artillery.
"There's a schedule of delivery to Ukraine which is on time, and the Ukrainians are very appreciative of the speed with which Bushmasters are being delivered," he told Sky News on Sunday.
"We're working with the Ukrainian government about how we can provide support over the long term.
Mr Marles said the aim of the support was to "enable Ukraine to ultimately end this conflict".
He also dismissed suggestions from the opposition that further support may be being held up by red tape in the defence department.
"It's not been held up and certainly, there's no complaint coming from Ukraine," he said.
It comes as Russia holds referendums in occupied Ukrainian territories as it tries to legitimise the annexation of four regions.
Ukraine and the international community, including Australia, have labelled the vote a sham, with Kyiv saying residents had been coerced.
The referendums were organised by Moscow after Russian forces lost ground in Ukraine's northeast following a large counter-offensive.
