Why did Russia occupy southern Ukraine so quickly?

On February 24, 2022, at 4 a.m., the Russian army began its attack on Ukrainian territory. The advance was conducted simultaneously in several directions: south, east, and north. However, it was in the south, where it seemed easier for Ukrainians to hold the narrow necks of Crimea, that the Russian offensive achieved the greatest success. The reasons for this remain unclear.

Several hours after the invasion began from the Crimean region, Russian military columns managed to reach Kherson and Nova Kakhovka, advancing 60-80 km inland.

Some of the Russian army units that entered through Crimea simultaneously developed an offensive to the east, capturing major cities such as Berdyansk, Melitopol, and Energodar, as well as the nearby Zaporizhzhia nuclear power plant, by the end of February and the beginning of March 2022. Then began the long and bloody siege of Mariupol, which would not be captured until mid-May.

After three years of extensive warfare, the territorial invasions in southern Ukraine remain one of the Kremlin's greatest achievements and one of the most mysterious pages of this conflict.

Neither Ukraine's political nor military leadership can fully answer the question of why there was a failure in the south. This has led to myths and speculations. BBC Ukrainian service commentator Oleg Chernish highlighted four key questions regarding the events in southern Ukraine in 2022 and attempted to answer them.

Were the bridges in Crimea mined?

There are only two roads connecting the peninsula to the mainland, leading from Armyansk through Perekop to Chaplinka and Kalanchak, and five main bridge crossings.

This refers specifically to the old and new automobile bridges in Chongar, the railway crossing on the dam west of the Sivash River, as well as two intermediate closures (prolets) of the automobile and old railway bridges towards Genichesk through the Arabat Spit.

Additionally, there are several fortified dams in the shallow bay of the Sivash Lake.

The Ukrainian military command emphasizes that all five bridges were mined before the invasion, and minefields along the Kalanchak and Chaplinka roads had been prepared as early as 2014.

According to the words of the former commander of the Joint Forces, Sergey Nayev (who held this position from March 2020 to February 2024 and is currently the commander of a tactical group at the front), the bridges were mined using a layered charge method, meaning explosives were placed on the surface, and approximately 1,500 mines were laid in the land areas.

However, he states that this amount of mines was insufficient under the conditions of a large-scale military aggression.

“In general, to repel the attack... there should have been more than 200,000 mines there,” the general said in an interview with “Ukrainskaya pravda” on February 10, 2025.

Besides the bridges and the Perekop neck, many elevated dams in the Sivash bay were also mined, says Leonid Gudanich, a former marine who served several combat rotations near Crimea from 2017 to 2020, in an interview with a BBC correspondent.

He states that defense positions and observation posts were prepared in this area, and the readiness of explosive barriers was constantly checked, especially during the rotation of units.

“That is, when you take over an object, you immediately check whether explosives have been installed, whether the cables are intact, because now it will be your responsibility,” explains the former marine.

He recalls that only once was a problem related to mining identified. This occurred at the Kutaran dam, which separates Lemur Lake from the Sivash Bay.

“We took a shovel and went to dig up the boxes with explosives. Some boxes turned out to be empty, and some were missing half of the explosive material,” he says.

The necessary amount of explosives was restored, and the incident was reported to the Ukrainian Security Service.

Gudanich does not rule out that Russian sabotage groups might have attempted to damage the explosive barriers at the border with Crimea, but emphasizes that much depended on the professionalism and vigilance of the Ukrainian units that served at the Perekop neck.

“Compared to the anti-terrorist operation (ATO), combat duty near Crimea felt like a rest. Did all the units approach their tasks with dedication while serving in this area?” rhetorically asks the former marine.

Why weren't all the bridges blown up?

“If the (Crimean) crossing routes had been disrupted and the initial hours had developed somewhat differently, it was clear that the Russian army would not have been able to move at such speed. This is an axiom,” emphasized the head of the Main Intelligence Directorate, Kirill Budanov, in August 2023.

If the bridges, dams, and crossings in Crimea were mined, why weren't they blown up?

General Sergey Nayev assures that he issued the first order for the preparation of all explosive barriers on February 23, 2022, and in fact, some of them were detonated during the Russian invasion.

He states that the railway bridge in Chongar and the automobile bridge on the Arabat route were blown up.

Ukrainian hero Vitaliy Skakun sacrificed himself to blow up the bridge at Arabat.

His comrades recall that Ukrainian fighters managed to deliver two trailers with cumulative charges (each containing approximately one ton of explosives) to the bridges near Genichesk after the order to blow them up was given on the morning of February 24.

“We connected everything, we are about to blow it up, but it doesn’t explode. We tried a second, third time — nothing happened,” recalls a marine fighter, Oleksandr Tkach, who served alongside Vitaliy Skakun in an interview in February 2024.

They check the wires, try again and again, but the explosion does not occur. Then Vitaliy Sakun takes the detonation device in his hand and runs towards the bridge. A minute later, the explosion occurs, and the fighter is also killed.

It later became known that the explosion only destroyed half of the bridge. This delays the Russian attack but does not stop it.

As for the railway bridge in Chongar, nothing is known except for what Nayev recently stated.

Ivan Sestrivatovskiy, a soldier of the marine battalion that was supposed to blow up the bridges in Chongar, first spoke to journalists in July 2023, stating that he had attempted to carry out the explosion three times, connecting and reconnecting the wires, but the explosion did not occur.

“I am not a sapper, but there are two options here. Either a sabotage group was dropped, or the wires were damaged as a result of fire from a mortar,” the fighter said at that time.

The minefields near the Chaplinka and Kalanchak routes also did not work.

Andrey Sokolov, the former commander of the Southern Operational Command (2021-22 — commander of the Southern Defense Forces, now a tactical group commander), suggested in 2023 that the Russians could have cleared these fields with artillery strikes, while the Ukrainian armed forces did not receive orders to mine the direct automobile routes before the enemy attack.

^{The Russian military column crosses the administrative border in Chongar without resistance. February 24, 2022
Photo: State Border Guard Service of Ukraine}
Ukrainian military journalist Yuriy Butusov stated that explosions occurred not only at the bridge at Arabat but also at the Kutaran dam: on the morning of February 24, two Russian infantry fighting vehicles (BMP) exploded there. There is no official information about this explosion. Military man Leonid Gudanich confirms that this dam was mined.

Why did the explosive barriers installed at the necks fail to work in most cases on the first attempt or did not explode at all?

General Sergey Nayev draws attention to the possibility that Russian sabotage groups operated and that the wires were damaged, as well as the heavy psychological state of the Ukrainian soldiers. They would have to carry out the detonation under a rain of bullets.

“We need to understand: military tasks during the war are not carried out immediately and 100 percent,” he added.

What was the ratio of forces in favor of the Russian army?

In April 2022, while explaining the failures in the south, the press service of the Ukrainian Armed Forces General Staff emphasized that the number of Russian troops in this area was 15 times greater than that of the Ukrainians.

Former commander Sokolov spoke of a 20-25 times superiority. According to him, 25 battalion tactical groups from the Russian Federation, amounting to up to 20,000 troops, attacked Ukraine from Crimea.

At the same time, the roads in the direction of Crimea were defended only by a small number of Ukrainian marines and border guards, totaling about 250 people. Additionally, many of the marines were inexperienced young soldiers.

They were not expected to engage in direct combat at the defense positions in the Crimean neck, says one of the marines who faced the large-scale assault in Chongar to BBC Ukraine service.

“We had clear instructions for the situation when the enemy breaks through: blow up the bridges and retreat to the prepared defense lines deeper in the territory,” he says.

They were supposed to be assisted by the 59th Motorized Infantry Brigade of the Ukrainian Armed Forces, but they could not leave the training ground near Oleshkovskiy sands — which is 60 km away from the administrative border with Crimea. Moreover, one of its most combat-ready battalions was sent to defend Melitopol, which was left completely unprotected.


^{Nayev was also responsible for the defense of the Kherson region in 2022 as the commander of the Southern Operational Command.
Photo: Ukrinform}
In such conditions, Ukrainian forces could only begin the first battles with the enemy near the Dnipro River, only near the Antonov bridge. However, considering that by that time the Russians had already captured Nova Kakhovka and crossed to the right bank of Kherson, it was inevitable that the Ukrainian armed forces would retreat into the territory on the right bank, otherwise large forces would be encircled.

On the left bank of Kherson, only 1,500 Ukrainian soldiers were insufficient to resist the Russian invasion, especially since the Russians attacked simultaneously in three directions: Kherson, Nova Kakhovka, and Melitopol.

According to the defense plan, this section of the front should have been held by at least four brigades of the Ukrainian armed forces, totaling 12,000 to 16,000 soldiers.

However, sending these forces to the southern direction was deemed impossible, according to the Ukrainian command.

General Viktor Nazarov, the chief advisor to the then commander-in-chief of the Ukrainian armed forces, Valeriy Zaluzhnyi (who was chief advisor from August 2021 to February 2024 and then became an advisor), recently told BBC that half of the 24 brigades of ground forces in combat composition at that time were engaged on the eastern front. The remaining 12 brigades had to be “scattered” to defend Kyiv, Chernihiv, Sumy, and the entire southern direction.

^{The Ukrainian army only partially damages the bridge in Chongar by striking with cruise missiles in June 2023. After that, the bridge was quickly restored. Photo: Reuters}
On the other hand, the crossing from Crimea is the narrowest point of the front where Russian troops entered. It is precisely here that since 2014, Ukrainian military forces and security structures have been trained to repel a potential invasion from this direction. In particular, it was stated in the book “Combat Chronicles of 2022” (authors — military historians Andrey Kharuk and Mikhailo Jirokhov):

“The Russian troops entered through the narrow neck, which was relatively easy to block from Crimea to the mainland of Ukraine. In previous years, the Ukrainian armed forces had conducted several relevant exercises. However, at the most responsible moment, the plan to block the exit routes from Crimea was not implemented.”

Was there treason in the government, special services, or the army?

Currently, several high-ranking former employees who worked in the leadership of the Security Service of Ukraine's Kherson and Crimea departments are being investigated. However, none of them are directly accused of the “failure in the south.”

The former head of the Security Service of Ukraine's Crimea department, Colonel Oleg Kulinich, was arrested in Kyiv in July 2022. Investigators suspect him of collaborating with Russian special services. He is accused of concealing information from the Ukrainian leadership about preparations for the invasion. In particular, about the accumulation of Russian troops and equipment in Crimea and the planned attack from the peninsula on the mainland of Ukraine at 4 a.m. on February 24.

Kulinich denies all accusations. Currently, his case is being reviewed in a closed session by the Kyiv court. The former special service officer is in custody.

A source in the special services told BBC that Kulinich has so far refused to sign an application for exchange with Russia, but it cannot be ruled out that he will agree after a verdict is issued.

^{Kulinich's arrest. Photo: State Investigation Bureau of Ukraine}
In March 2022, President Volodymyr Zelensky referred to the former head of the Security Service of Ukraine's Kherson department, Sergey Krivoruchko, as a “traitor” and “anti-hero,” stripping him of his general's rank.

However, according to BBC information, he has not been held criminally responsible.

“There is nothing to announce against him, no facts of him working for the Russians have been established. He was actually just inactive in that situation,” emphasizes the source in the special services.

Currently, Krivoruchko is in reserve (meaning he has not been dismissed from military service in the Security Service of Ukraine but is not being appointed to any position) and has been reported to have been suspended from duty, according to the SBU in response to a BBC inquiry.

In an interview with “Gromadskiy” publication in August 2023, Krivoruchko denied any involvement in any wrongdoing.

The situation involving Colonel Igor Sadoxin of the Security Service of Ukraine is even more complicated.

During the large-scale invasion, he was in charge of the Anti-Terror Center under the Kherson department of the SBU. This center had coordinated anti-terror exercises conducted at the border with Crimea several months before the invasion.

According to media reports, in March 2022, Colonel Sadoxin was arrested by law enforcement officers in the Chernivtsi region on suspicion of treason. This was also reported by the head of the patrol police, Yevgeniy Zhukov, on Facebook, but his post has since been deleted.

Oleksandr Samoylenko, head of the Kherson regional council, stated in an interview with “Ukrinform” in June 2022 that this particular SBU officer might have “provided the Russians with a map of minefields” in the south.

“It is believed that he provided the enemy with a network of minefields and coordinated the movements of the Russian aviation while escorting the evacuation of the Kherson security service column,” said the head of the regional council.

^{Although Sadoxin was arrested in March 2022, he remains on the wanted list. Photo: Ukraine Interior Ministry Database}
However, Colonel Sadoxin is currently at large. In any case, the Ministry of Internal Affairs indicates that he disappeared from the attention of law enforcement agencies at the beginning of 2023 and has been placed on the wanted list.

In response to a BBC inquiry, the Security Service did not clarify where Sadoxin is now, but stated that the agency had suspended him and placed him in reserve. The State Investigation Bureau (SIB) is investigating him for “abandoning his post” (Article 407, Part 5 of the Criminal Code). The Main Intelligence Directorate has not yet responded to BBC's inquiry regarding this case. Sadoxin himself has not commented on the situation publicly.

The State Investigation Bureau has also been investigating the actions of the high military command during the Russian invasion from Crimea since April 2022. The actions of the military regarding the mining of bridges and the preparation of defense at the crossing from Crimea are being examined. In particular, the investigation is looking into the actions of military leadership, including General Nayev and the then commander-in-chief, General Valeriy Zaluzhnyi.

Currently, investigative actions are ongoing. Hundreds of witnesses have been interrogated, expert examinations have been conducted, but there are no suspects.

^{The State Investigation Bureau is investigating not only the failure of the Kherson region's defense but also the “improper defense” of Mariupol, which was quickly surrounded by Russian troops at the beginning of the invasion.}
Additionally, BBC has been informed that another criminal case has been opened regarding the “insecure defense” of Mariupol.

It is known that due to the rapid breakthrough from Crimea, the Russian army was able to approach Mariupol much faster from the western flank and surround the Ukrainian garrison stationed in the coastal city. The defense forces had to resist in a full encirclement until mid-May, when they were captured by the Russians.

However, the Main Intelligence Directorate refused to disclose the details of these two criminal cases and emphasized that the pre-investigation check remains confidential.

The bureau also declined to comment on whether General Yuriy Sodol, who was responsible for this section of the front, and Denis Prokopenko, the commander of the “Azov” brigade that commanded the defense of the city, had been interrogated.

Until the Ukrainian law enforcement agencies and courts can provide a final resolution to these cases, it is unlikely that Ukrainian society will receive a complete and reliable answer to the question of who is to blame for Russia's rapid occupation of southern Ukraine and its continued hold on it.