Ukraine forces are reportedly putting up strong resistance to invading Russian forces as they surround and bomb the capital Kyiv on Sunday.
According to United States military information, Russia now has at least 50 percent of its estimated 150,000-strong invasion force inside Ukraine.
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Analysts interviewed suggested the Russian military may have been caught off-guard by the level of pushback by Ukrainian fighters, and more troops would likely enter the fray in the coming days.
“Russia is clearly facing setbacks that it did not expect. It’s taking casualties and Ukraine is taking prisoners, including some quite senior, at least one, possibly two, brigade commanders,” said Nigel Gould-Davies from the International Institute for Strategic Studies.
“So Russia will be motivated now to accelerate the forces that it brings to this conflict. So far, it’s been using about half of the forces it has mobilised and prepared for this so in numerical terms.
“It’s quite clear that Russia has a very significant advantage. But the really impressive aspect of Ukraine’s resistance so far is how strong and how wide it has been,” said Gould-Davis, a former United Kingdom ambassador to Belarus.
Tom Bullock, an open source intelligence analyst for intelligence information firm Janes, said Russian forces so far have not been able to capitalise on their vastly superior military advantage.
He said fighting has slowed around major cities after Russian troops and equipment stormed the country on Thursday.
“The trend we are seeing is that the Russians are incurring losses, they are losing equipment and definitely losing soldiers. But so are the Ukrainians. In some places such as the south it appears the losses are heavier on the Ukrainian side.
“It does appear as though the Russians were expecting less resistance from the Ukrainians when they entered. That clearly hasn’t been the case,” Bullock told Al Jazeera.
‘Lack of momentum’
Troops and equipment are making slow progress on Moscow’s original three-front thrust because of “very determined resistance”, an American defence official told reporters on condition of anonymity to discuss internal US assessments.
“We have indications that the Russians are increasingly frustrated by their lack of momentum over the last 24 hours, particularly in the north parts of Ukraine,” the official said.
Al Jazeera was not able to independently verify the claim.
Russia said its forces pursued their advance after claiming to have paused their assault on Ukraine following an order from President Vladimir Putin. The Russian president subsequently ordered the attack to resume after Kyiv ignored Moscow’s call for negotiations. A Ukrainian official denied Kyiv had rejected talks.
In Moscow on Saturday, the defence ministry said the Russian army had been ordered to broaden its offensive.
“Today all units were given orders to develop the advance from all directions in accordance with the operation’s plans,” Russian Army Spokesperson Igor Konashenkov announced.
Russia has so far not succeeded in fully taking any Ukrainian city, although its forces have been bearing down on Kyiv as well as Kharkiv, which lies close to the Russian border.
Russia has claimed control of southern urban centres, including Melitopol and Kherson, north of the annexed Ukrainian peninsula of Crimea, but this has not been confirmed.
The conflict has been marked by radically different versions of events from both sides.
Ukraine’s health minister said on Saturday 198 civilians, including three children, have been killed so far by Russian forces.
Russia has not said how many of its soldiers have been killed in the invasion, which it calls a “special military operation”. Moscow has said its goal is to “de-Nazify” Ukraine.
Western sources agree days of fierce fighting looms for control of Kyiv with Ukraine President Volodymyr Zelenskyy, who has insisted on staying in the capital, in physical danger.
‘Repelling enemy attacks’
The bulk of the Russian troops reportedly remained 30km (18 miles) outside of Kyiv.
A defiant Zelenskyy said his forces were repelling Russian troops advancing on the capital.
“We have withstood and are successfully repelling enemy attacks. The fighting goes on,” Zelenskyy said in a video message from the streets of Kyiv posted on his social media.
“Our main goal is to end this bloodbath. The enemy is suffering heavy losses – hundreds of soldiers killed who crossed our border and entered our land. Unfortunately, we are also suffering losses. Ukrainians are courageously resisting the aggression,” said Zelenskyy.
The US and Western allies are still able to deliver arms into the country to bolster the Ukraine military, and Washington plans to send more in the coming days to help them fight both Russian armour on the ground and assaults from the air, the US official said.
US Secretary of State Antony Blinken announced on Saturday that Washington will provide $350m in additional military equipment to Ukrainian forces.
Ukraine, a democratic nation of 44 million people, won independence from Moscow in 1991 and wants to join NATO and the EU – goals Russia opposes.
Putin has said the West failed to take seriously Russia’s security concerns about NATO. But he has also expressed scorn about Ukraine’s right to exist as an independent state.