Ukrainian forces are capable of launching a lightning strike to try to seize the Ukrainian capital, Kiev, within a few days.
Special forces are expected to be part of a Russian offensive that could quickly encircle Ukraine’s best-trained troops in the east of the country and prevent them from defending Kiev.
The rapid capture of Kiev after a possible major bombing of key locations in the city would severely damage the country’s political and military decision-making capabilities, and possibly pave the way for the establishment of a pro-Russian administration.
But the attack also threatens to kill scores of Ukrainians and Russians, which could last for years.
Some Russian troops in Belarus are believed to have already reached the Ukrainian border.
Other Russian units are believed to have left the central areas to move closer to the field, which puts them in a better position to advance in Ukraine.
Russian military chiefs are expected to try to avoid a street fight in the Ukrainian capital, which could result in civilian casualties as well as military casualties.
However, past military operations have shown that if they deem it necessary to capture the city, they will order such a civilian incursion, even if it means horrific bloodshed.
Boris Johnson warned on Monday that the situation in Ukraine was “very dangerous” because Britain feared a Russian attack was now “very close”.
He urged Vladimir Putin to withdraw from “one side of the border” by deploying a force around Ukraine that is thought to be far more than the army used to occupy Crimea in 2014. That this is the largest military formation since the end of the war. Gulf War.
The Russian president has denied any involvement in the attack.
However, the sheer size of the Russian military, with more than 130,000 troops, and its make-up indicate that it has been mobilized for the attack, although Mr Putin has not yet decided whether to order it.
It is believed that about 100 battalion tactical groups have already been deployed as part of major preparations and at least 14 more are advancing, accounting for more than 60% of the total Russian ground firepower. Represents
Russia and Belarus have deployed short-range ballistic missiles, and the Kremlin has sent more ships to the Black Sea, including landing craft.
The British Armed Forces Minister James Happy stressed on Monday morning: “Perhaps more unfortunately, although it has received fewer headlines, all combat capabilities, logistics, fuel, medical equipment, bridge assets are now in place. Are on. “
Russian officers are thought to be operating on the pretext that they are preparing for an attack, rather than a military exercise.
Important decisions can be made in days, possibly even on Wednesday.
Attacks could come from Belarus in the north, Russia in the east, or Crimea in the south, although they cannot all be ordered at the same time.
The Kremlin could launch a “false flag” operation to justify sending troops to Ukraine to defend pro-Russian territories or, apparently, to retaliate against Ukraine’s alleged aggression.
Mr Johnson and US President Joe Biden were in crisis talks on Monday afternoon.
Downing Street said security chiefs were briefing the prime minister during the day on the threat of an attack on Ukraine.
An official spokesman for the prime minister said the attack was a “serious possibility” this week, even with warnings that sanctions on Moscow, including its financial sector, could hurt.
He said there was still a window of opportunity to reduce tensions and take the diplomatic route.
But he stressed: “There are no signs that we are talking about reducing stress.”
Given the scale of the military deployment, some experts have questioned whether Mr Putin can now withdraw his forces without losing face.
However, the Russian president could argue that he has forced the West to talk about European security, the deployment of force and missiles, and the transparency of measures.
However, if he orders an attack, his biggest gamble will be, in part, how many Ukrainians will receive Russian troops.
Some Ukrainians will do it, but others have not, and the Kremlin may not have guessed how many will oppose it, leading to a bloody quagmire of war with Russian troops trapped in Ukraine for years at heavy economic and human cost. There may be danger.