US President Joe Biden is "convinced" that Russian President Vladimir Putin has decided to launch an invasion in Ukraine, saying he has "reason to believe" it will occur in the "coming days" and will include an assault on the capital Kyiv.
His comments were echoed by Australia's Prime Minister Scott Morrison who said it appears the likelihood of an invasion is "imminent".
After weeks of saying the United States was not sure if Mr Putin had made the final decision to launch a widespread invasion, Mr Biden said that assessment had changed.
"As of this moment I'm convinced he's made the decision," Mr Biden said on Friday. "We have reason to believe that."
He cited the United States' "significant intelligence capability" for the assessment.
Mr Biden reiterated his threat of massive economic and diplomatic sanctions against Russia if it did invade, and pressed Putin to rethink his course of action.
He said the United States and its Western allies were more united than ever to ensure Russia paid a price for the invasion.
Speaking on Saturday, Mr Morrison told reporters in Darwin that "what we are seeing in Ukraine is looking regrettably inevitable".
"We hope this is not the case. We hope that Russia will step back from its violent threats of intimidation on its neighbour, Ukraine. But it does appear, particularly in the reports that we've seen that the likelihood of an invasion in Ukraine by Russia is imminent."
Mr Morrison said "the pretence has been sought for an invasion".
"There is no pretence for an invasion into Ukraine. There is no justification for it. There is no provocation of it," he said.
Mr Morrison said Australia would stand by its like-minded allies and would provide "support that is necessary".
"Australia has not been asked or nor would we be providing support through troops or anything of that nature," he said.
"We work with our allies and partners in many other ways, and we will seek to do that with the practical things that we can do to assist those efforts.
"We have had such discussions with the UK prime minister and others about how we proceed along that basis."
Russia behind cyberattacks on Ukraine, UK and US say
Russian military intelligence was behind the recent cyberattacks that knocked Ukrainian banking and defence ministry websites offline, the United States and United Kingdom said earlier on Friday.
US Deputy National Security Advisor Anne Neuberger told journalists at the White House that Washington was seeking to hold Russia to account for its aggressive moves in cyberspace.
"Russia likes to move in the shadows and counts on a long process of attribution," Ms Neuberger said on Friday.
"In light of that, we're moving quickly to attribute the DDoS (distributed denial of service) attacks. We believe the Russian government is responsible for widespread attacks on Ukrainian banks this week."
Ms Neuberger said Americans had data showing that infrastructure connected with Russia's military agency, generally known as the GRU, "was seen transmitting high volumes of communication to Ukraine-based IP addresses and domains".
In a simultaneous announcement, British officials said the GRU was "almost certainly involved" in the DDoS, which works by flooding targeted websites with a firehose of data.
Kyiv had already blamed Moscow for the DDoS amid heightened tensions since Russia began massing troops near the border, raising fears Russia was planning to attack.
Ms Neuberger said the attacks had "limited impact" but it was possible the Russians were laying the groundwork for more destructive ones.
It comes amid artillery shelling in the east of Ukraine and orders from Russian-backed separatists for civilians to evacuate the region ratcheted up already crackling tensions over the massing of Russian troops Friday ahead of what the United States says is a likely invasion.
Deputy National Security Advisor for Cyber & Emerging Tech Anne Neuberger. Source: Getty Images North America
The Kremlin continues to insist that it has no plans to attack its neighbour.
However, the US says that with an estimated 149,000 Russian troops on Ukraine's borders - as many as 190,000, when including the Russian-backed separatist forces - it's likely not a matter of if there'll be a large-scale attack, but when.
Washington is "ready" for fallout if Russia decides to "weaponise" its massive energy reserves in response to Western sanctions, a senior US official said Friday.
"If Russia decides to weaponise its energy supply, we're ready," White House deputy national security advisor for international economics Daleep Singh told reporters.
"We've been taking steps ... to coordinate with major energy consumers, major energy producers to ensure that we have steady energy supplies and ... stable energy markets," he said.
Adding to jitters, Russia's defence ministry announced that President Vladimir Putin would personally oversee previously scheduled drills involving nuclear-capable missiles on Saturday.
On the ground in Ukraine's disputed east, sporadic clashes fed a growing sense of dread.
An AFP reporter near the front between Ukrainian government forces and the pro-Russian territory in the Lugansk region heard explosions and saw damaged civilian buildings on Kyiv's side of the line.
There were growing fears that only a spark - which Washington warns could be a deliberate "false flag" incident created by the Russians - might now be needed to set off the largest military confrontation in Europe since World War II.
NATO chief Jens Stoltenberg, attending the Munich Security Conference, warned the size of the assembled Russian force far exceeded that needed for military drills, and that Russia had the capacity to invade without warning.
Map showing positions of Russian troops around Ukraine. Source: SBS News
Accusations fly
In the eastern separatist areas of Donetsk and Lugansk, Moscow-backed leaders sought to flip the narrative of Russia being the aggressor.
Accusing Kyiv of planning its own offensive to retake the eastern territories, they said the government's forces were carrying out sabotage missions. The evacuations of civilians were said to be in response to worries about a government attack.
But US Secretary of State Antony Blinken accused the Kremlin of mounting a propaganda campaign to create an excuse for war.
Mr Blinken told the Munich conference what has happened "in the last 24 to 48 hours is part of a scenario that is already in place of creating false provocations, of then having to respond to those provocations and then ultimately committing new aggression against Ukraine."
Ukraine's foreign minister said "Russian disinformation" about a supposed Ukrainian attack was being spread to fuel the war fever.
Putin sees 'deterioration'
Videos circulating on Russian-language social media showed sirens sounding in Donetsk as Moscow-backed militia leaders ordered the civilian evacuation over the border to Russia.
Denis Pushilin, head of the so-called Donetsk People's Republic (DPR), declared: "Women, children and the elderly are subject to be evacuated first."
He claimed Ukraine's president, Volodymyr Zelensky, would soon "give the order for soldiers to go on the offensive."
The leader of neighbouring Lugansk Leonid Pasechnik also urged residents to evacuate to Russia "to prevent civilian casualties".
Ukraine's President Volodymyr Zelensky. Source: Sipa USA Konstantin Sazonchik/TASS/Sipa U
In Moscow, Mr Putin met with the authoritarian leader of Belarus, which is hosting tens of thousands of Russian troops on the Ukrainian border.
"We are seeing a deterioration of the situation," Mr Putin said at a joint press conference.
'Could have been much worse'
On Thursday, a shell punched a hole in the wall of a kindergarten in government-held territory near the frontline in the Ukrainian village of Stanytsia Luganska.
The 20 children and 18 adults inside escaped serious injury but the attack sparked international protest.
"It hit the gym. After breakfast, the children had gym class. So, another 15 minutes, and everything could have been much, much worse," school laundry worker Natalia Slesareva told AFP at the scene.
On Friday, part of the village remained without electricity.
The Ukrainian joint command centre said the rebels had violated the ceasefire 53 times between midnight and 5:00 pm Friday, while the Donetsk and Lugansk separatist groups said the army had fired 27 times in the morning.
"Ukrainian defenders returned fire to stop enemy activity only in case of a threat to the lives of servicemen," the command centre said.
Russian 'strategic' forces
The Russian defence ministry sent a chilling reminder of the stakes in any East-West confrontation when it announced that Putin would oversee Saturday's "exercise of strategic deterrence forces ... during which ballistic and cruise missiles will be launched."
The air force, units of the southern military district, as well as the Northern and Black Sea fleets, would be involved in the nuclear-capable missile tests.
Russia says that it will not back away from Ukraine unless Western countries agree never to allow Ukraine into NATO and to pull US forces back from eastern Europe, effectively creating a new version of the continent's Cold War-era spheres of influence.
The conflict between the heavily armed pro-Russian rebels and Ukrainian government forces in the country's east has already rumbled on for eight years, claiming the lives of more than 14,000 people and forcing more than 1.5 million from their homes.
