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Nato estimated on Wednesday that 7,000 to 15,000 Russian soldiers have been killed in four weeks of war in Ukraine, where fierce resistance from defenders has denied Moscow the lightning victory it sought.
By comparison, Russia lost about 15,000 troops over 10 years in Afghanistan.
A senior Nato military official said the alliance’s estimate was based on information from Ukrainian authorities, what Russia has released — intentionally or not — and intelligence from sources.
Ukraine has released little information about its own military losses and the West has not given an estimate.
But Ukrainian President Volodymyr Zelenskyy said almost two weeks ago that about 1,300 Ukrainian servicemen had been killed.
When Russia invaded on February 24 in Europe’s biggest offensive since the Second World War, a swift toppling of Ukraine’s government seemed probable.
But with Wednesday marking four full weeks of fighting, Moscow is bogged down in a grinding military campaign.
With its ground forces slowed or stopped by hit-and-run Ukrainian units armed with western-supplied weapons, Russian President Vladimir Putin’s troops are bombarding targets from afar, falling back on the tactics they used in reducing cities to rubble in Syria and Chechnya.
In an ominous sign that Moscow might consider using nuclear weapons, a senior Russian official said the country’s nuclear arsenal would help to deter the West from intervening in Ukraine.
“The Russian Federation is capable of physically destroying any aggressor or any aggressor group within minutes at any distance,” said Dmitry Rogozin, the head of the state aerospace corporation Roscosmos.
Mr Rogozin said Moscow’s nuclear stockpiles included tactical nuclear weapons designed for use on battlefields, and far more powerful nuclear-tipped intercontinental ballistic missiles. Roscosmos oversees missile-building plants.
Dmitry Polyansky, Deputy Permanent Representative of Russia to the UN, backed the nuclear warning against the military alliance.
“If Russia is provoked by Nato, if Russia is attacked by Nato… we are a nuclear power, why not?” he told Sky News.
“When you’re dealing with a nuclear power of course you have to calculate all the possible outcomes of your behaviour,” he added.
US officials have long warned that Moscow's military doctrine includes an “escalate to de-escalate” option of using nuclear weapons to force the enemy to back down in a situation where Russian forces face imminent defeat. Moscow has denied having such plans.
Mr Rogozin did not elaborate on what actions by the West would be seen as meddling, but his comments almost certainly reflect thinking inside the Kremlin.
Mr Putin has warned the West that an attempt to introduce a no-fly zone over Ukraine would draw it into a conflict with Russia. Western nations have ruled out establishing the zone.
As US President Joe Biden left for Europe to meet key allies about new sanctions against Moscow and more military aid to Ukraine, he warned there was a “real threat” Russia could use chemical weapons.
On the eve of a meeting with Mr Biden, EU nations approved another €500 million ($550m) in military aid for Ukraine.
The US has also determined that Russian troops have committed war crimes in Ukraine, and it will work to prosecute the offenders, Secretary of State Antony Blinken said.
Mr Blinken gave evidence of indiscriminate or deliberate attacks against civilians and the destruction of apartment buildings, schools, hospitals, shopping centres and other sites.
Addressing Japan’s Parliament, Mr Zelenskyy said thousands of his people had been killed, including at least 121 children.
“Our people cannot even adequately bury their murdered relatives, friends and neighbours," he said.
"They have to be buried right in the yards of destroyed buildings, next to the roads."
Major Russian objectives remain unfulfilled. The capital, Kyiv, has been bombarded repeatedly but is not even encircled.
Near-constant shelling and gunfire shook the city Wednesday, with air raid sirens wailing and plumes of black smoke rising from the western outskirts, where the two sides battled for control of several suburbs.
Mayor Vitali Klitschko said at least 264 civilians had been killed in the capital since the war broke out.
The shelling also claimed the life of another journalist on Wednesday.
The independent Russian news outlet The Insider said Russian journalist Oksana Baulina was killed in a Kyiv neighbourhood.
In the south, the encircled port city of Mariupol has seen the worst devastation of the war, enduring weeks of bombardment and now street-by-street fighting.
But Ukrainian forces have prevented its fall, thwarting an apparent bid by Moscow to fully secure a land bridge from Russia to Crimea, which was seized from Ukraine in 2014.
Mr Zelenskyy said 100,000 civilians remain in the city, which had a population of 430,000 before the war. Attempts to get desperately needed food and other supplies to those trapped have often failed.
Mr Zelenskyy accused Russian forces of seizing a humanitarian convoy.
Deputy Prime Minister Iryna Vereshchuk said the Russians were holding captive 11 bus drivers and four rescue workers, along with their vehicles.
Head of Nato concerned Russia may use chemical weapons in Ukraine
In their last update, more than a week ago, Mariupol officials said at least 2,300 people had died, but the true toll is probably much higher.
Air strikes in the past week destroyed a theatre and an art school where civilians were sheltering.
In the besieged northern city of Chernihiv, Russian forces bombed and destroyed a bridge that was used for aid deliveries and civilian evacuations, regional governor Viacheslav Chaus said.
Kateryna Mytkevich, who arrived in Poland after fleeing Chernihiv, wiped away tears as she spoke about what she had seen.
The city is without gas, electricity or running water, and entire neighbourhoods have been destroyed, said Ms Mytkevich, 39.
“I don’t understand why we have such a curse,” she said.
Despite much evidence to the contrary, Kremlin spokesman Dmitry Peskov insisted the military operation was going “strictly in accordance” with plans.
The Nato official said 30,000 to 40,000 Russian soldiers are estimated to have been killed or wounded. In its last update, Russia said on March 2 that nearly 500 soldiers had been killed and almost 1,600 wounded.
Ukraine also claims to have killed six Russian generals. Russia acknowledges only one has died.
The figures from Nato represent the alliance’s first public estimate of Russian casualties since the war began.
The US government has largely declined to provide estimates of Russian or Ukrainian casualties, saying available information is of questionable reliability.
With losses mounting and quick victory no longer in sight, Russia is trying to suppress dissent and shore up morale.
It has arrested thousands of anti-war protesters and cracked down on the media.
And under a law passed on Wednesday, troops in Ukraine will get the same benefits as veterans of previous wars, including tax breaks, discounts on utilities and preferential access to medical treatment.
UN chief: ‘War in Ukraine is unwinnable’
In an apparent reflection of growing divisions in Russia’s top echelons, Anatoly Chubais has resigned, Mr Peskov told the Interfax news agency.
Mr Chubais, the architect of Russia’s post-Soviet privatisation campaign, served in a variety of leading posts over three decades. His latest role was as Mr Putin’s envoy to international organisations.
Mr Peskov would not say if Mr Chubais had left the country.
Western officials say Mr Putin’s troops are facing serious shortages of food, fuel and cold-weather gear, some suffering frostbite, while Ukraine’s defenders have been going more on the offensive.
But Russia’s far stronger, bigger military has many western experts warning against overconfidence in Ukraine’s long-term odds.
Talks to end the fighting have continued on video. Mr Zelenskyy said negotiations with Russia were moving “step by step, but they are going forward".
In the coastal city of Odesa, the scene of sporadic Russian shelling, merchant sea captain Sivak Vitaliy carried sandbags over each shoulder, loading them on to trucks for barricades being erected in case of an enemy assault.
Building after building has been destroyed in cities such as Mariupol and Kharkiv, but Ukrainian soldiers defending their own soil will not be defeated, Mr Vitaliy said.
“No matter how bad the situation is in Mariupol, Kharkiv, it doesn’t matter. We will win.”
