Explainer: Why a Russian retreat from Kherson matters to the war in Ukraine

Ukrainian officials said Friday that Ukrainian flags were appearing "en masse and all over the place," in the wake of Russia's retreat from the southern region of Kherson, one of the four regions in Ukraine that Russian President Vladimir Putin annexed in September.

The months-long Ukrainian offensive to recapture the city of Kherson, the only provincial capital that has been under Russian control since the early days of the invasion, is coming to a head. The fall of the city would deal another humiliation to Moscow after a string of battlefield defeats and other setbacks.

Here's a look at what is happening and why Kherson is such an important city for both sides.

Why is the city such a prize?

Kherson, which had a prewar population of 280,000, is the only regional capital to be captured by Russian forces. The city and surrounding areas fell into Moscow's hands in the opening days of the war as Russian troops quickly pushed their attack north from the Crimean Peninsula the region illegally annexed by the Kremlin in 2014.

Its loss was a major blow to Ukraine because of its location on the Dnipro River near the mouth of the Black Sea, and its role as a major industrial centre. Ukrainian resistance fighters have challenged Russian troops for control of the city ever since, with acts of sabotage and assassinations of Moscow-appointed officials.

Kherson also sits at a point where Ukraine can cut off fresh water from the Dnipro to Crimea. Kyiv blocked those vital supplies after the Crimean Peninsula's annexation, and Putin mentioned the need to restore them as one reason behind his decision to invade Ukraine.

What is happening now?

In the last 24 hours, Ukrainian troops have made gains northwest, west and northeast of the city of Kherson, advancing up to sevenkilometresin some areas, according to the Institute for the Study of War, a Washington-based think tank.

"Russians have moved to positions they hope will be easier to defend. Ukraine will have to decide whether, when, and how to keep pushing," said Olga Oliker, director for Europe and Central Asia at the International Crisis Group. "But Ukraine seems on the verge of taking back ... and this is very good news for Mykolaiv, which Russia will now have a much harder time bombarding. It is a serious Ukrainian advance."

In an evening video address Friday,Ukrainian PresidentVolodymyr Zelenskyy called it a "historic day" and said "we are getting the south of thecountry back, we are getting Khersonback."

"As of now, our defenders are on the outskirts of the city, and we are very close to entering. But special units are already in the city," he said.

In video obtained by Reuters and released on Friday, peoplewere shown cheering and celebrating Ukrainian soldiers in Kherson's Freedom Square.

WATCH | Khersonresidents greet Ukrainian troops with joy:

Ukrainian soldiers greeted with joy in Kherson

2 years ago

Duration 0:50

Residents cheer at the arrival of Ukrainian troops in Kherson's Freedom Square after Russia abandoned the only regional capital it had captured since the beginning of the conflict.

What have the Ukrainian troops found?

Kherson's Ukrainian-appointed regional official, Serhii Khlan, said as Russia pulled its troops from the western bank of the river that divides the region, they have left wreckage in their wake, destroying key infrastructure, including power facilities and bridges.

"It will all have to be reconstructed," he said Friday at a video briefing. "While fleeing, they were blowing up everything, everything that could deter the [Ukrainian]advance."

Khlan advised civilians to stay home and said the humanitarian situation was complicated, with power supplies cut off and very limited communications.

What does the Kremlin say?

The Kremlin remained defiant Friday, insisting that battlefield developments in the Kherson region in no way represented an embarrassment for Putin.

Fearing such a major Ukrainian counterattack, the Kremlin-installed regional administration in Kherson reportedly relocated at least 70,000 residents earlier this month.

What would losing Kherson mean for Russia?

A retreat from Kherson and other areas on the Dnipro's west bank would shatter Russian hopes to press an offensive west to Mykolaiv and Odesa to cut off Ukraine's access to the Black Sea. Moscow had also hoped to build a land corridor to the separatist Transnistria region of Moldova, home to a major Russian military base.

"The loss of Kherson will turn all those southern dreams by the Kremlin into dust," said Ukrainian military analyst Oleh Zhdanov. "Kherson is a key to the entire southern region, which would allow Ukraine to target key supply routes for the Russian forces. Russians will try to retain control of it using all means."

What would recapturing Kherson mean for Ukraine?

For Ukraine, capturing Kherson would set the stage for reclaiming the Russia-occupied part of the Zaporizhzhia region and other areas in the south, and eventually pushing back into Crimea.

Reclaiming control of Kherson would also mean that Kyiv could again cut off water to Crimea.

"After the de-occupation of Kherson, the Russians will again have problems with fresh water in Crimea," Zhdanov added.

What will China think?

Volodymyr Fesenko, head of the Kyiv-based Penta Center independent think tank, noted that controlling the Kherson region and other southern areas was a major prize for Russia and their loss would have painful consequences for Putin at home and abroad.

"If the Russians leave Kherson, the Kremlin will face another wave of fierce criticism of the military command and the authorities in general from ultra-patriotic circles," Fesenko said, adding that the fall of the city would further demoralize Russia's armed forces and possibly fuel opposition to the mobilization effort.

He also said China and India would see the fall of Kherson as a sign of Kremlin weakness.

"Putin will face reputational losses not only inside the country, but also in the eyes of China, and that could be particularly dangerous for the Kremlin," Fesenko said.