Military helicopters fly over tanks and armored vehicles moving during the Union Courage-2022 Russia-Belarus military drills at the Obuz-Lesnovsky training ground in Belarus on February 19. Photo / AP
How a full-blown war between Russia and Ukraine will unfold is still unclear. But with up to 190,000 Russian troops massed on Ukraine's borders and an additional 15,000 Russian-backed separatists already in the occupied Donbas region of eastern Ukraine, Vladimir Putin has for the past few days been widely expected to give the order to invade.
Communication attack
The propaganda war has been raging for some days, with Moscow claiming that five Ukrainian troops have been killed in Russian territory and three civilians murdered by Ukrainian "saboteurs" in the Donetsk People's Republic.
US intelligence agencies have warned that a massive cyber attack on key Ukrainian infrastructure as a prelude to full-scale invasion was likely. The Kremlin hopes to sever Ukraine's communications with the outside world, jamming mobile signals and launching a cyber attack on internet services. It will also try to disrupt the Ukraine military's internal communications.
The Atlantic Council, a US think-tank, has claimed Russia could cut off most of Ukraine's internet traffic by slicing through a single undersea cable in the Kerch Strait installed by Moscow's state-owned telecommunications firm.
Ukraine's electricity grid, communication systems and government ministries have been targets of suspected Russian cyber attacks in the wake of the 2014 invasion of Crimea. Much of Ukraine's critical infrastructure, including its electricity grid, remain connected to Russia, making it virtually impossible to defend from attacks.
Aerial bombardment
Russia is expected to launch wave after wave of mostly unguided long-range missile strikes before a ground assault.
Any aerial bombardment is likely to be short-lived, lasting a few hours.
Russia will fire shells from long range, well back from the front line, targeting any Ukrainian military out in the open but also deployed against known "choke points" such as strategic railway lines, crossroads, airfields and bridges in an attempt to cut off Ukraine's forces and prevent reinforcements.
Missiles can be fired from the ground hundreds of miles away. The BM-30 Smerch artillery launcher fires 300mm rockets from 12 barrels simultaneously with a range of up to 530 miles.
The Iskander rocket launcher has a shorter range of 300 miles but a more explosive warhead. Both systems were spotted being driven into the Donbas region on Tuesday, putting Kyiv within reach.
Russia is expected to deploy drones to spot Ukrainian command and control centres and military communication hubs in the field and target artillery.
Missiles will be fired from the Donetsk and Luhansk regions occupied by Russian separatists, and now being claimed by Moscow, but also from the long border in the north east and from Belarus, where Russian forces have been amassing in recent weeks.
Ground assault
Russia's ground campaign will begin once it is satisfied that the artillery has cleared a path for tanks and armoured vehicles to roll into Ukraine.
Analysts believe its forces will attempt to surround and isolate Ukraine's troops, destroying them in pockets. Russia will hope to have knocked out Ukraine's air force and air defence systems. With air superiority established, it is likely Russian special forces will be dropped by helicopter behind Ukrainian lines to further disrupt command centres and other strategic targets with sabotage operations.
It is estimated that of the 190,000 troops on the borders, about 30,000 are stationed in Belarus, no more than 150 miles from Kyiv.
"The main effort of Russia's ground campaign would be to create a pincer movement from the north that encircled Kyiv and enveloped the bulk of Ukraine's ground forces in the eastern part of the country," say Michael Kofman and Jeffrey Edmonds, experts in the Russian military at the US Centre for Naval Analyses, in a paper published this week.
Along with the armoured firepower will come specialist engineering equipment to build bridges, repair roads and rail tracks, clear minefields and keep the Russian army on the move. Russia has a few hundred state-of-the-art T-14 Armata tanks and thousands of Soviet-era T-72s and T-80s upgraded with modern armour and weaponry.
The Centre for Strategic and International Studies, a Washington-based think tank, has identified "three likely axes of advance" for Russia to seize territory up to the Dnieper river and into Kyiv: a northern route that would include outflanking Ukrainian defences from Belarus; a 200-mile central route through Donetsk; and a third assault from Crimea in the south.
It suggests that Kharkiv, close to the Russian border but a hub for road and rail, is critical if Russia wants to win a war quickly. If Kharkiv resists, strategists believe Putin's army will struggle to strike out to Kyiv, particularly as February is one of the coldest months with daylight limited to 10 hours a day.
Air and sea
Russia's Black Sea fleet has been strengthened since the annexation of Crimea and is expected to play an important supporting role in any invasion. It consists of dozens of anti-submarine frigates and guided missile destroyers while Russian submarines have also been spotted in the area.
Cruise missiles with a range of 1,000 miles would supplement any aerial bombardment from the north and east. Kofman and Edmonds believe the fleet is capable of launching a "significant amphibious operation" and could deploy 1,000 to 2,000 ground troops to assist forces launching an invasion across the isthmus connecting Crimea to the Ukrainian mainland.
Experts describe Ukraine's navy as a "mosquito navy", made up largely of small gunboats.Fighter jets and helicopters could be sent in to destroy anything not taken out by the aerial bombardment.
They will also hope to win the remaining battle of the air early on. Ukraine has fewer than 100 combat aircraft, including 43 state-of-the-art, Russian-made Mig-29s and 15 combat helicopters. Russia in contrast has 10 times the firepower, including 70 Mig-29s and 80 Mig-31s.
Guerilla warfare
Strategists suggest that Russian forces will try to avoid Ukraine's major cities in the push west. If the Ukrainian army finds itself overwhelmed in the first few hours, its forces will likely retreat to the cities and draw a line at the Dnieper river and try to protect Kyiv and other urban areas on the river.
Street-by-street conflict would be messy and bloody, with ideal conditions for resistance fighters defending Ukraine. Ukrainian forces have been training for this outcome in abandoned cities near Chernobyl. The longer any conflict drags on the greater the problem for Russia in keeping up supply lines as well as the cost in life and to its economy.
The Centre for Strategic and international Studies says that "Russia may be unable to avoid sustained urban combat in several major metropolitan areas (and the resulting high casualties) if it attempts more than a punitive incursion into Ukraine".
Kyiv has a population of three million and a further 1.5 million people live in Kharkiv. Odessa and Dnipro are also major cities. "If defended, these large urban areas could take considerable time and casualties to clear and occupy," says the think tank.