Russia is on the cusp of an "all-out conflict" in Ukraine, according to Defence Minister Peter Dutton.
As the United States government warned a Russian invasion could occur in the coming days, Mr Dutton said there were multiple signs this was on the cards.
"It's tragic and we'll see terrible scenes unfolding," Mr Dutton told the Nine Network on Friday.
"You would expect that President (Vladimir) Putin, who obviously can't be taken at his word, is manufacturing some sort of trigger, or is in the process of executing the final stages of his plan to go into Ukraine."
Prime Minister Scott Morrison echoed this, saying a Russian invasion of Ukraine is "imminent" and reapplied pressure on China to denounce violent actions in eastern Europe.
He told reporters: "It's important for all nations to denounce the threats of terrible violence that Russia is making against Ukraine.
"It remains a highly volatile situation and an invasion of Ukraine is, of course, imminent."
It comes after the US said Russia is on the verge of unleashing a massive military attack against Ukraine, as artillery fire hit a Ukrainian kindergarten.
In a dramatic, previously unscheduled speech to the United Nations in New York on Thursday, US Secretary of State Antony Blinken said intelligence showed Moscow could order an assault on its neighbour in the "coming days."
With US and other Western governments saying they see no evidence to support Russia's claim to be withdrawing, Mr Blinken challenged the Kremlin to "announce today with no qualification, equivocation or deflection that Russia will not invade Ukraine. State it clearly. State it plainly to the world."
"Demonstrate it by sending your troops, your tanks, your planes, back to their barracks and hangars, and sending your diplomats to the negotiating table," he said.
President Joe Biden, at the White House, accused Moscow of preparing a "false flag operation" as a pretext for an attack and said this could happen "in the next several days."
"They have not moved any of their troops out. They've moved more troops in," Mr Biden said. "Every indication we have is that they're prepared to go into Ukraine."
He added, however, that diplomacy is not dead. “There is a path. There is a way through this".
US Secretary of State Antony Blinken. Source: Getty Images
'Forced to respond'
Russia has massed enormous air, land and sea forces around Ukraine. President Vladimir Putin and officials say they do not plan to invade Ukraine and that the troops are only conducting practice exercises.
However, Mr Putin has made clear that the price for removing any threat would be Ukraine agreeing never to join NATO and for the Western alliance to pull back from a swath of eastern Europe, effectively splitting the continent into Cold War-style spheres of influence. Ukraine is far from being ready to join NATO but has said this is part of a broader goal to integrate with the democracies of western Europe, making a historic break from Russia's orbit.
The US said on Thursday that it had received Mr Putin's response to its offers of a diplomatic solution to the crisis, but did not give any reaction to the contents.
The Russian foreign ministry indicated that there was little to discuss.
"In the absence of will on the American side to negotiate firm and legally binding guarantees on our security from the US and its allies, Russia will be forced to respond, including with military-technical measures," the foreign ministry said.
"We insist on the withdrawal of all US armed forces in Central Europe, Eastern Europe and the Baltics," it added.
Russia also expelled the number two US diplomat in Moscow, the US State Department said, condemning the "unprovoked" action.
Armoured vehicles move at the Gozhsky training ground during the Union Courage-2022 Russia-Belarus military drills in Belarus, which neighbours Ukraine. Source: AAP
Artillery fire on kindergarten
Russia took over Ukraine's Crimea region and began backing heavily armed separatists in the eastern Donetsk and Lugansk regions in 2014, sparking a war that has already cost thousands of lives.
Sporadic fighting remains common in the east and the Ukrainian army accused the pro-Russian separatists of 34 ceasefire breaches on Thursday, 28 of them using heavy weapons.
The potentially most serious incident, an example of the kind of spark that many fear could ignite far more intense fighting, was the shelling of a kindergarten in the village of Stanytsia-Luganska. Children were inside but none were hit.
Ukrainian President Volodymyr Zelensky tweeted that the attack "by pro-Russian forces is a big provocation."
Russian news agencies meanwhile quoted authorities in the separatist Lugansk region saying they blamed Kyiv after the situation on the frontline "escalated significantly".
US Defence Secretary Lloyd Austin described Thursday's reports as "troubling".
A Ukrainian soldier stands next to a damaged wall after the reported shelling of a kindergarten in the settlement of Stanytsia Luganska. Source: AFP
"We've said for some time that the Russians might do something like this in order to justify a military conflict. So we'll be watching this very closely," Mr Austin told journalists after a meeting with NATO counterparts.
Mr Putin earlier this week claimed with no evidence that Ukraine is committing "genocide" in the eastern region.
Disputed pull-out
Moscow has made several announcements of troop withdrawals this week and on Thursday said that units of the southern and western military districts, including tank units, had begun returning to their bases from near Ukraine.
Defence ministry spokesman Igor Konashenkov said some troops had returned to their garrisons in several areas far from the border, including Chechnya and Dagestan in the North Caucasus, and near Nizhny Novgorod, some 300 kilometres east of Moscow.
After previously announced withdrawals earlier this week, the US, NATO and Ukraine all said they had seen no evidence of a pullback, with Washington saying Russia had in fact moved 7,000 more troops near the border.
Mr Zelensky said Thursday his country was not looking for foreign forces within its borders.
"We have no need for soldiers with foreign flags on our territory. We are not asking for that. Otherwise, the entire world would be destabilized," he told the RBK Ukraine website.
