UK defence ministry says Russian army faces Ukraine 'war of attrition'

The coming weeks will be decisive, experts say

Firefighters put out a major blaze caused by Russian shelling at a food warehouse in Severodonetsk, a city in eastern Ukraine's Luhansk region. AFP

Irina Zubchenko walks her dog Max amid the destruction caused by the shelling of a shopping center in Kyiv. AP

Ukrainian refugee Masha, 6, plays at the border crossing in Budomierz, Poland. Reuters

A charred Russian armoured personnel carrier on the front line in the Kyiv region. Reuters

A volunteer takes position at a checkpoint in a district of Kyiv as Russian forces try to encircle the Ukrainian capital. AFP

Residents of Kyiv retrieve belongings from their homes in a five-storey residential building that partially collapsed after shelling by Russian artillery. AFP

Police officers in Moscow detain a woman as she protests against Russia's invasion of Ukraine. AFP

A resident of the village of Krasylivka after Russian bombardment, part of Moscow's effort to move on Kyiv. AFP

Tetiana Chornovol, a former Ukrainian MP, prepares to take position with an anti-tank missile on the front line in the Kyiv region. Reuters

A rescue worker at a shopping mall in Kyiv after a Russian air strike. Reuters

Ukrainian firefighters rescue a person buried beneath rubble after an explosion at a shopping centre in Kyiv. Reuters

Ukrainian police officers stand near a warehouse that was hit by the debris of a downed rocket in Kyiv. AFP

Graves are dug in a street in the besieged southern port city of Mariupol. Reuters

Pro-Russia militia fighters travel by tank to the outskirts of Mariupol. Reuters

Milana, 6, who is recovering from leg wounds sustained when a Russian rocket hit her house on February 28, killing her mother, watches volunteers dressed as clowns at a children's hospital in Kyiv. Getty

Tetyana and other residents wait in Kyiv, after being relocated from Irpin town. EPA

Rescuers carry a Ukrainian soldier saved after 30 hours trapped in the wreckage of a military school hit by Russian rockets, in Mykolaiv. AFP

A Ukrainian refugee arrives with her dog at the reception centre about three kilometres from the Moldova-Ukraine border. EPA

Volunteers in Kyiv prepare packages with food and other goods for Ukrainian soldiers and civilians in cities across the country. EPA

Residents walk between damaged residential buildings in Mariupol. Reuters

Participants illuminate the Ernst Happel Stadium in Vienna with the lights of their smartphones, during the charity concert We Stand with Ukraine. AFP

Yana Hladiychuk of Ukraine with a "Stop War" message on her face after the women's pole vault, on the second day of the World Athletics Indoor Championships in Belgrade. Getty

An Ukrainian girl in tears after crossing the border in Siret, northern Romania. AFP

A satellite image shows the aftermath of the Russian air strike on the Mariupol Drama Theatre. EPA/Maxar Technologies

A woman takes cover in a military trench as a Russian jet fighter flies overhead, near the military school hit by Russian rockets the day before, in Mykolaiv. AFP

A man walks amid debris in front of a Kyiv residential apartment complex that was heavily damaged by a Russian attack on March 18. Getty

Residents carry water from a food warehouse, which is under the control of the breakaway Donetsk People's Republic, on the outskirts of Mariupol. AP

Rescuers work at the site of the National Academy of State Administration building damaged by shelling in Kharkiv. AP

A satellite image shows artillery strikes and burning fields in Chernihiv. AP / Maxar Technologies

A resident assesses her damaged flat in Mariupol. Reuters

Kyiv's mayor Vitali Klitschko keeps people away from a five-storey residential building that partially collapsed after shelling on March 18. AFP

Russian President Vladimir Putin addresses crowds at a concert in Moscow to mark the eighth anniversary of the annexation of Crimea. AP

Ukrainian policemen secure a residential area in Kyiv. Sergei Supinsky

Ukrainian President Volodymyr Zelenskyy. AP

A cloud of smoke rises after an explosion in Lviv, western Ukraine, on March 18. AP

Zinaida Pivtsova, 75, who fled the war in Ukraine, takes shelter in a sports stadium in Przemysl, south-east Poland. AP

A police officer at abandoned residential buildings in Kyiv. AP

Inside a shell-damaged school in Kyiv. AP

A woman cries before starting to clean the site where a bomb damaged residential buildings in Kyiv. AP Photo / Rodrigo Abd

A woman from Ukraine sits in a car with her children as a volunteer takes them to a hostel in Budapest, Hungary. AP

An abandoned flat in Kyiv. AP

A man removes a curtain inside a school in Kyiv. AP

A worker sets up a billboard with the colours of the Ukrainian flag in Novoiavorisk, near Lviv. AP

Olga plays with her daughter Vedeneya in an empty park in Kyiv. AP

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The war in Ukraine has now raged for close to one month and many analysts say the conflict could be reaching a turning point, as Russia prepares a new military offensive.

“The Kremlin has so far failed to achieve its original objectives. It has been surprised by the scale and ferocity of Ukrainian resistance,” the UK’s Ministry of Defence said on Saturday.

“Russia has been forced to change its operational approach and is now pursuing a strategy of attrition," the ministry said. A war of attrition means the outcome of the conflict depends on which side can sustain manpower, despite high losses, as both sides wear each other down.

With the exception of the south of the country, where Russia is making gains in the port city of Mariupol and has taken control of the cities of Kherson and Melitopol, Russia's advances have stalled on most fronts.

Russia is poised to occupy most of Ukraine’s coastline, with the large port city of Odesa being one notable obstacle. But Ukraine has also launched a number of successful counterattacks, notably near the city of Mykolaiv.

A current threat for Ukraine is the risk that Russian forces could cut off large numbers of Ukrainian soldiers, trapping them against the Dnieper river, which bisects the country.

"Ukrainian forces opposite Donetsk and Luhansk are at risk of encirclement on the eastern side of the Dnieper," said Sam Cranny-Evans and Sidharth Kaushal, writing on the UK's Royal United Services Institute website.

Whether or not Russian forces achieve this encirclement, losses on both sides are extremely high and mounting.

Recent US estimates put Russian losses between 2,000 and 7,000 while President Volodymyr Zelenskyy said Ukraine had suffered 1,300 dead soldiers by March 12.

The high losses on many fronts raise the question of whether Russia has aimed for too many objectives, rather than aiming to capture Kyiv with one major thrust.

"Napoleon told one of his more sluggish generals, 'if you're going to take Vienna, take Vienna,' Lt Gen Michael Barbero told The National.

"Because if you're gonna go for it, you better have everything, your logistics, your fires, the simultaneity of effects, you better have that all synchronised and lined up," he said, noting that Russia's considerable force might be too dispersed across the country.

Manpower challenge

Russian forces are trying to seize a number of large cities including Kyiv, which has a population of more than three million people, Kharkiv, which had a prewar population of 1.5 million and Odesa, a large port city of nearly one million people.

Experts say that in order to take control of enemy-held terrain, attacking forces need at least three times the number of soldiers as the defender.

In urban operations, this ratio could be higher: an Iraqi force of about 100,000 backed by western air power and advisers took nine months to take control of Mosul, a city defended by as few as 12,000 ISIS fighters, by one estimate.

The force ratio problem is now a challenge for Russia, said Rob Lee, a senior fellow at the Foreign Policy Research Institute.

“It is becoming a numbers game for Russia. Partial encirclements of Chernihiv, Sumy, and Kharkiv all require Russian forces as does the fighting in Mariupol. Other forces have to be used to secure supply lines from ambushes and hold occupied cities,” he said on Saturday.

But even with new innovations such as using drones to act as “spotters” for artillery, it is generally thought to be easier to defend an area than to attack, and Ukraine also uses similar tactics.

Tooth to tail

In addition to the so-called “three to one rule," Russia's objectives are complicated by two factors, what analysts call the “tooth to tail ratio” of a force and the fact that Ukraine has mobilised its reserves since February 24, as well as recruiting large numbers of volunteers.

The tooth to tail ratio is the number of soldiers available for front line combat at any given time (“tooth”) versus the "tail," the number of soldiers working in support roles — supplying fuel, food and ammunition, as well as securing rear areas.

The more Russia advances, the more soldiers will be held back to guard supplies and bases.

UK defence attache Mick Smeath recently said that Ukrainian harassment of supply lines was “severely limiting Russia’s offensive potential.”

A study by the McKinsey consultancy on modern militaries, including France, the US, Spain, Japan, South Korea — and Russia, found that on average forces could sustain a combat commitment of 26 per cent of the force.

If this is correct, Russia can send about 40,000 men in combat of the 150,000 men now inside Ukraine. But those front-line forces are also taking extremely heavy casualties.

Meanwhile, Ukraine’s military has swelled its ranks to about 300,000, outnumbering the Russian invasion force.

Ukraine of course also has the “tooth to tail” ratio to consider, but defenders have shorter supply lines meaning their logistical requirements could be easier to sustain.

“Once they get into the cities, offensive operations in urban terrain are a meat grinder,” retired Lt Gen Michael Barbero said.

“The time the Ukrainians have had to prepare roadblocks, blowing up bridges, preparing kill zones to channel the Russians into, and ambushes, is going to turn it into a more casualty-producing situation. And when you're in urban conflict, the consumption of supplies goes up ten-fold,” he says.