Ukraine faces a moment of “true peril” in the weeks ahead as Russian military commanders plan to encircle its best troops, analysts have said.
Up to 45,000 soldiers — a third of Ukraine’s professional army along with some of its recently acquired equipment — are in Donbas, on the front line with separatists and Russian forces in the east.
If the siege of Mariupol ends quickly, many Russia troops will be freed for a pincer movement from the north and south to entrap Ukrainian forces in the area referred to as the Joint Forces Operation (JFO) — the troops sent to the eastern line of contact that bounded the separatist-held areas of Donetsk and Luhansk.
The war could then turn, with Russia’s larger forces and amount of equipment overwhelming Ukraine’s superior fighting skills.
This scenario increases the importance of Mariupol, as the longer it holds out, the more losses Russia will suffer, weakening its southern pincer.
Mariupol’s tenacity will also buy time for the JFO to either strengthen defences or leave before being cut off.
“We are entering the period of true peril for Ukraine where [the prospect of] encirclement and destruction for its forces starts to become more realistic,” said Sam Cranny-Evans, an analyst at the Royal United Services Institute, a London think tank.
“I think we're going to begin seeing the situation really start to shift in Russia's favour.”
Defence strategist Brigadier Ben Barry agreed with Mr Cranny-Evans's assessment that a moment of alarm had arrived for Ukraine's military.
“The Ukrainians must be concerned, or they ought to be concerned about this,” said Mr Barry, senior fellow for land warfare at the International Institute for Strategic Studies think tank.
“Because if Mariupol falls, then that releases Russian forces to do different things, one of which could be to continue to push north up along the lines of the Dnieper Valley in an effort to threaten the forces in eastern Ukraine in Donbas.”
What can Ukraine do?
Central to Ukraine's efforts to counter Russia artillery will be the ability to locate and destroy it, analysts said. Ukraine has — and is reported to be acquiring more — US-made radar that can precisely locate or trace artillery and rocket fire.
If the Ukrainians have preserved their self-propelled howitzers and missiles, this might allow them to counter the Russian artillery threat.
However, it is a question of resources and of whether sufficient stocks are getting into Ukrainian hands from the West.
So far, the supply of anti-tank and anti-aircraft missiles has allowed Ukraine to keep Russia at bay.
More radar, drones and long-range precision missiles could make a significant difference to Ukrainian operations.
Ukrainian forces have also chosen to fight in small units that can mount swift attacks on armoured columns.
Once Russia co-ordinates its electronic warfare systems with its artillery and its drones, it will be able to locate and attack Ukrainian troops.
Moscow’s generals will also be seeking to force the Ukrainians to “mass in a place that suits Russia”, where it can “decisively engage them when they emerge”, Mr Cranny-Evans said.
“If the Russians are able to start surrounding these major town and the Ukrainians can't get through to their forces, then time begins to shift in favour of Russia because Russia can continue those bombardments indefinitely.
“That really changes the tempo of the operation.”
Battle at Kramatorsk
If Mariupol falls and the Russian forces to the south of Kharkiv push on, Ukraine’s best troops could find themselves besieged at Kramatorsk.
Faced by a pincer movement and entrapment, they would have to decide on fight or flight.
If a force remains, there will be heavy fighting and Russia’s greater numbers could overwhelm Ukraine’s best troops, especially the combat-hardened JFO.
“They will start losing casualties because the JFO have either got to stay or escape,” said Tim Ripley, an analyst with Janes Defence Weekly.
“If they try to escape, they'll be vulnerable to being spotted and attacked. That's the point where Russia’s advantages in artillery and air power come into play.
“That's why the Ukrainians are fighting like tigers in Mariupol, trying to tie down as many troops as possible so the Russians cannot use them to attack the JFO.”
If the encirclement of the JFO stops any supplies getting in, then the end could come “quite quickly”, Mr Cranny-Evans said.
“You will end up with a very one-sided fight and we'd probably know about the result before it was over.”
The JFO encirclement is something western defence sources also fear but believe Kyiv’s generals will be alert to the danger.
“It’s the area of the battlefield where we've got the greatest concern,” a defence source told The National. “There's a vulnerability for those forces to encirclement.”
But a sudden Ukraine withdrawal could also end in “road of death territory” if the Russians started co-ordinating their hardware, said Mr Ripley, author of Little Green Men: Putin’s Wars since 2014.
The extent of losses on both sides is unclear. Ukraine's military dead could be as high as 4,000 and Russia’s 10,000, some estimates show.
Much of the imagery shown on platforms such as Telegram or TikTok are managed by both sides and, without proper intelligence, it is like “looking through a drinking straw”, Brig Barry said.
Both sides are managing information to “match their messaging”, with Ukraine showing the world that it is the victim but that it could hold out with western help.
The Russian “punishment strategy of bombardment” was possibly to improve their position before negotiations.
“Or it may be marshalling its supplies to recommence operations with a large offensive somewhere — or several large offensives,” Brig Barry said.
“We also shouldn't forget also the political significance of Kyiv and we can't rule out a renewed effort to encircle the capital.”
Spring weather will mean the snowmelt “rasputitsa” mud that has forced Russian tanks on to roads will recede, allowing greater force mobility across Ukraine.
Russia will be able to restock its supply lines, but that also applies to Ukraine’s armour and lorries, particularly the brigades in the JFO.
Although there have been Russian atrocities, the war has also so far remained “limited”, in that neither side has escalated to the level of mass direct attacks on civilians such as the bombing of refugee trains or Ukraine launching missile against Russian cities.
A major escalation could present Nato with hard choices.
But should Ukraine's JFO brigades be destroyed, Russia may declare that the country has been “demilitarised”. Moscow would also have control of much of the east of Ukraine.
“If you can militarily defeat some of the best Ukraine troops in the army, that would stand grounds to say that they've demilitarised Ukraine,” Brig Barry said.