There's one final step Vladimir Putin will have to make if he's serious about war with Ukraine, according to a US Marine chief.
For months, Russia has amassed a total of 100,000 troops on its border with the fellow former Soviet Union state - with experts torn as to whether an invasion is actually in the offing.
Or, if Putin is simply flexing his military might as a political bargaining tool.
During scheduled 'war games' early last year, Moscow was able to shift battle tanks and artillery under the radar, with the bulk of what could form an attack support network left idly in position in open dispersal camps.
Tens of thousands of troops also failed to go home after the manoeuvres were over.
Russia is now mobilising specialist equipment and other supplies, including ammunition carriers to its 'frontline'.
It is bringing the crucial combat platforms and enabling capabilities and units it will need to move forward with an assault.
Added to this are the last-minute training exercises Russia has announced in subservient Belarus - a large-scale war game named Allied Resolve 2022.
There have also been fresh cyberattacks striking in Ukraine in recent days.
According to the Snowcroft Center for Strategy and Security, these are all major clues for imminent war.
But there's one last move Putin hasn't played yet and, according to Colonel John Barranco, it's a deal-breaker.
"Russia is going to need to call up reservists out of civilian life if it is serious about invading and occupying all or most of Ukraine," the senior US Marine Corps fellow at the Atlantic Council think tank says, reports NZ Herald.
"That's going to have an economic impact and cause discontent among the public, so Moscow is unlikely to do it unless it's serious."
Many of Russia's most high-profile modern weapons are being moved into position, with the war games allowing for plausible deniability.
But members of the think tank also agree there's an element of parading to Moscow's behaviour.
Moving vulnerable assault ships from the Barents and Baltic Seas, for example, they say doesn't make much sense when it would be easier to move equipment by rail.
Instead, the presence of such vessels could be a sign of "gunboat diplomacy".
Russia wants legally-binding guarantees that Ukraine will not be allowed to join NATO.
Putin has made it clear he sees such a deal - which would mean his old foe is backed by a 30-strong military alliance - as a threat to Russia’s borders.
The Russian leader last month warned the US sanctions against the Kremlin over its build-up of border troops would be a “huge error” that would lead to a breakdown of relations.
Ukraine split from the now-defunct USSR in 1991 and set about building new allegiances with western nations, leading to continued tensions with Russia.
In 2014, the Kremlin seized Ukraine's Crimean peninsula and in response to mass protests saw Ukraine oust its pro-Russian president.
Russia retaliated by backing a separatist insurgency in Ukraine's east, with continued skirmishes on the border ever since.
A 2015 peace agreement was brokered but Russia then accused Ukraine of breaking it, with compliance from the West.
On Monday, the Kremlin claimed Ukraine is more ready to launch an assault than ever before.
