It comes as social media footage footage shows suspected large scale Russian military movements in regions close to rebel-held eastern Ukraine and annexed Crimea.
With tension sharply rising, analyst Pavel Felgenhauer, 69, said it now requires a 'psychoanalyst' to determine Russia's intentions in Ukraine but warned events could see 'war in a month'.
The West has expressed alarm about Moscow's movement of troops and forces, and Felgenhauer says they are right to be concerned as unverified new footage appears to show military movements in Russia's Voronezh, Rostov and Krasnodar regions, along with key railway routes.
'The crisis has the potential to escalate into a pan-European war, if not even a world one,' Felgenhauer warned starkly in an interview with Rosbalt news outlet in Russia.
'But for now, potential. Will it happen or not? Let's wait and see. In the West, they don't know what to do about it.'
A European or even World War could be triggered in four in Ukraine after Russia dispatched 4,000 to the disputed border with its neighbour, warns an independent Russian military analyst. Pictured: Military machinery being moved by suspected Russian troops
It comes as social media footage footage shows suspected large scale Russian military movements in regions close to rebel-held eastern Ukraine and annexed Crime.
Military analyst Pavel Felgenhauer
Russia yesterday vowed to 'take extra measures' if Nato sends forces to Ukraine after the Kremlin dispatched 4,000 troops to the disputed border with its neighbour.
'No doubt such a scenario would lead to a further increase in tensions close to Russia's borders. Of course, this would call for additional measures from the Russian side to ensure its security,' Kremlin spokesman Dmitry Peskov told reporters.
He insisted, however, that Russia was 'not threatening' Ukraine, despite an earlier statement which warned a war in Donbass would 'destroy' its neighbour.
Footage has emerged showing shows dozens of military helicopters close to the frontier, and the movement of tanks and other military vehicles by train.
The United States pledged its 'unwavering' support to Ukraine on Thursday as defense officials said they were aware of thousands of troops newly-deployed to the separatist Donbass territory, which is controlled by pro-Moscow factions.
Asked why Russia may be pushing for a conflict now, Felgenhauer replied: 'Address this question to a psychoanalyst. Do I need to explain?
'The facts are there, everything is already happening.'
Footage has emerged showing the movement of tanks and other military vehicles by train
He claimed all the conditions could be in place by early May when Russian will hold a major Red Square parade to mark the anniversary of victory in World War Two, and he suspected a 'decision has been made already'.
Felgenhauer said factors pushing Russia towards seizing land from Ukraine were 'the closure of pro-Russian TV channels in Ukraine, the threat of arrest and trial of Ukrainian politician Viktor Medvedchyuk, the arrest of Alexei Navalny, [and] President Biden calling Putin a murderer'.
'The threats are growing, and rapidly. Much is not discussed in the media, but we are seeing very bad signs,' he added.
In the third week of March, three large Russian Baltic Fleet landing ships passed south through the English Channel, accompanied by a corvette, he said.
'There will be ten such combat units in total, plus small airborne troops,' he said. 'You can collect up to two divisions, taking into account the air force.'
Russia could be planning a 'Normandy-style landing' between Odessa and Mykolaiv, he claimed.
Putin has huge forces in occupied east Ukraine - which fell under his sway in 2014, and in Crimea which was occupied.
The Biden administration pledged its 'unwavering' support to the Ukraine on Thursday (pictured: Russian president Vladimir Putin, left, and Joe Biden, right)
'Obviously, a major operation is being prepared, and other forces will be brought in as well,' he said.
'Everyone is talking about a possible tank invasion from Belgorod through Kharkiv in the direction of Zaporizhia in order to surround Ukrainian forces on the left bank of the Donbass.'
Putin might 'cut off Ukraine from the sea, create [a new rebel state of] Novorossiya, for example' or he could make a move then pause and start dictating terms to the West, Felgenhauer added.
Or Russia could seek to extend his control devouring Ukraine as far as Transnistria, a landlocked, Moscow-controlled no man's land 'unofficial state' with its own KGB secret service, he claimed.
Felgenhauer predicted that the West's expected reactions to such moves were 'unclear'.
'Some [in the West] say that the Russians should not be provoked, and military intervention is too risky.
'Others, on the contrary, are in favour of unification (of Russia and Ukraine) and open confrontation, because then it will be possible to bargain with Russia.'
Ukraine alleges Russia has 32,700 troops in Crimea, and commands 28,000 separatist servicemen in rebel-held eastern Ukraine.
'Despite significant enemy forces, the Ukrainian army is prepared for all potential scenarios,' said Ruslan Khomchak, the Ukrainian commander-in-chief.
Putin's spokesman Dmitry Peskov defended the troop movement towards border areas.
The Russian Federation moves troops within its own territory at its own discretion,' he said.
The Kremlin said Thursday Ukraine and the West should not 'worry' about Russian troop movements on the Ukrainian border (pictured, a tank of pro-Russian militants of the self-proclaimed Donetsk People's Republic)
'This shouldn't concern anyone, as such actions do not endanger anyone.'
He claimed: 'As you know, intense activity of the armies of NATO member states and other organisations, as well as particular states etc, is being observed on the perimeter of Russian borders.
'We need to stay on guard.'
A NATO official said that the Western allies have 'concerns' over Russian 'large scale military activities around Ukraine'.
An American expert on Russia, Michael Kofman said that while there was 'no strong evidence that an attack is imminent' it was clear 'something is up outside of regular exercises or normal troop rotation'.
He warned: 'Russian intentions are unclear.'
Ukraine, Western countries and NATO accuse Russia of sending troops and heavy weapons to prop up its proxies in Donbass who seized a swathe of eastern Ukraine in 2014.
Russia says it only provides political and humanitarian support to separatist fighters in what it casts as an internal conflict.
Ukrainian military intelligence accused Russia of engineering provocations to create a pretext to send additional Russian military units to Donbass.
'In addition, an attempt to advance Russian occupation forces deep into Ukraine is not ruled out,' it said.