- [Narrator] After weeks of intense fighting,
resulting in battered equipment and logistical issues
in the capital of Kyiv and other northern cities,
Russian forces changed tack.
(Volodymyr speaking in foreign language)
- [Narrator] The Donbas region,
with flat countryside terrain,
is a more familiar battleground
for Russia's military,
which has trained a large portion
of its forces in open-air combat.
(gun booming)
And its landscape is more suited
to conventional battles, involving artillery systems.
Moscow is estimated to have thousands
of tanks already deployed in the region
where Russian-led separatists
have been waging war since 2014.
- To a large degree, it is tank country.
That is you can really conduct mechanized warfare operations
that is really the types of operations
that the Russian armed forces traditionally
are quite good at.
- [Narrator] The move comes after Russian forces
face several setbacks in cities across the country.
Among the key issues, failing to establish dominance
in the skies and not preparing
for stiff resistance from Ukrainian fighters,
military experts say.
So as Russia shifts its approach to focus on the east,
we analyze what went wrong for Moscow in Kyiv
and why it believes it can succeed
in this next phase of war.
These images show a convoy of Russian tanks,
infantry-fighting vehicles, self-propelled artillery,
and logistical support heading toward Kyiv
in late February.
The column was thwarted by Ukrainian resistance efforts
just days after Moscow began its invasion
of its smaller neighbor.
- Part of Russia's biggest failure
to take Kyiv was that it stuck to the roads,
as military analysts say.
Satellite imagery showed us these large columns,
long columns of tanks
and armored vehicles going for kilometers and miles
on these roads.
And Ukraine did a really good job
of ambushing them from the forests
and from the sky with drones.
- [Narrator] Striking the long supply lines
created logistical problems for Russia
as it tried to support its forces inside the country.
- Russian forces at the front were struggling
to get basic things like even food and water,
let alone equipment.
- [Narrator] Early Russian advances to take control
of the capital and other northern cities
were also hampered by poor tactics,
according to analysts.
- They haven't really trained for it on a large scale.
The Russian armed forces
are essentially an artillery army supported
by mechanized forces,
that is tanks and other armored vehicles.
So they always were short on infantry
because the way they fight,
they're not really meant to go
into cities and conduct urban combat operations.
- [Narrator] That, paired with an unexpectedly
resolute defense from the Ukrainian forces,
armed with nimbler weapons,
including Turkish-made armed drones
and US-made javelins left Russia vulnerable
in the city, and saw their forces retreat in late March.
Russian officials have pushed back
against Western and Ukrainian claims
that it has failed.
- I don't think we failed, frankly.
We conduct our military operation, it's not a war,
it's a military operation.
It has its own strategy, it has its own aims.
- [Narrator] Russia's Defense Ministry
didn't immediately respond to requests for comment
about their changing strategy in Kyiv
and the Donbas region.
Following failures to take Kyiv,
Russia refocused its strategy
to try to take control of the Donbas region.
- Russia has been fighting a conflict
for eight years there already.
Pro-Russian separatists broke away
in two parts of the east, Donetsk and Luhansk,
back in 2014 after Russia seized Crimea from Ukraine.
- [Narrator] Military analysts say controlling the region
and Mariupol could be key for connecting
what they describe as a land bridge
between the south of Ukraine and Russia.
- Uniting the east and then southern front lines
of Russian forces,
I think it would make it easier also
to resupply the Russian troops in the south.
- [Narrator] There are also environmental factors at play.
In contrast to Kyiv, where dense, urban wooded areas
proved difficult for Russian forces,
the Donbas region is more open,
which some analysts compare to a World War II battlefield.
If it can coordinate its forces,
that could allow Russia to leverage its military equipment.
- The situation is a bit more advantageous
for the Russian armed forces,
but, of course, there's also some deficits
and the Russians are running low
on precision-guided munitions.
- [Narrator] And Moscow faces a protracted fight
with thousands of battle-hardened forces in the region.
Analysts say Ukraine is believed
to have between 40 and 50,000 soldiers in the Donbas,
many of whom have spent years fighting
against Russian-backed separatists.
But a big factor in who can control this next phase
of war analysts say is who can achieve air superiority,
a key detail that has so far been hard
for open source investigators to track.
- You really would want to dominate the skies
above your troops as they're advancing.
Make sure that no enemy aircraft can attack your troops,
making sure that no enemy missiles
can hit your troops.
- [Narrator] For Ukraine to be able to withstand
such attacks from Russia in the east,
keeping the flow of advanced weapons
from the US and other countries is key analysts say.
Ukrainian president Volodymyr Zelenskyy
has demanded continued assistance from allies
as the country enters a different stage of war.
But despite Russia's shifting military focus,
Putin's initial ambitions,
which Western officials said were to take the capital
and install a new government may remain missing.
(dramatic music)