The fighter wears a field cap, sunglasses and a scarf over his mouth and nose. His voice in the video is distorted – nothing should reveal his identity. His message is clear: "We will occupy buildings, we will fight on the streets and bridges. We will not give away a single piece of our land." He and his allies, he says, are fighting against the pro-Russian administration in the Kherson region of southern Ukraine. "Anyone involved is already on our death list," he says.

The video, recorded in early July and distributed through Telegram channels, gives a face to the resistance, albeit a concealed one. Alternating between Ukrainian and Russian, the language of the aggressors, the member of the Yellow Ribbon movement provides concrete information about a Russian military camp in the city. The message to the occupiers: We know who you are and where you are, you will never be safe.

In the first weeks of the summer, the number of attacks mounted by partisan fighters has been increasing in the Russian-occupied territories, particularly in Kherson, the provincial capital on the Dnipro River, with a population of 280,000. On June 18, the head of the prison there, appointed by the Russians, was injured in an explosive attack. Four days later, a car bomb killed a high-ranking member of the regional administration. And 10 days ago, an attack on a vehicle belonging to the head of the region's pro-Russian administration was thwarted. He had already narrowly survived an attack in June.

In the northeast of the country, in the occupied portion of the Kharkiv region, an official installed by Russia was killed early last week. Meanwhile, there have also been attacks on infrastructure vital to the war effort. For example, a railroad bridge in the south between Tokmak and Melitopol was blown up in early June.

The Partisans Are Kyiv's Fifth Column

Most such operations tend to remain secret, but DER SPIEGEL was able to speak with Ukrainian agents, in addition to people formerly and currently active in the resistance in the Russian occupied territories, in the free parts of Ukraine and abroad. Their reports underscore just how diverse the resistance to Vladimir Putin's troops has already become – and how threatening the situation could still get for the occupiers. Recently delivered Western weapon systems like the American HIMARS, a multiple rocket launcher with a range of 80 kilometers (about 50 miles), allow Ukrainian forces to attack targets deep inside the occupied areas. There have been increasing reports in recent days of Russian ammunition and fuel depots being destroyed and command centers coming under fire. All of which clearly shows that assistance from Ukrainians in those areas – such as passing on locations of Russian troops and depots – is crucial at this stage of the war. The resistance has become Kyiv's fifth column.

Yet it took quite some time for the Ukrainian authorities to realize the military value of their own people – and no one knows this better than Volodymyr Zhemchugov. The 51-year-old is the best-known member of the Ukrainian resistance struggle. The partisan fighter hails from the village of Khrustalny in the Luhansk region and fought against the Russian occupiers eight years ago. When the occupation by Moscow-directed separatists began in the Donbas province in 2014, followed later by regular Russian soldiers, he was living in Georgia as the owner of a packaging materials company. But when he returned to his home country for a visit, he says he witnessed "alcoholics" taking control of his town, murdering friends of his and forbidding the burial of the bodies of Ukrainian soldiers.

"The fear in my mother's eyes was my motivation to do something," Zhemchugov says. He decided to put together a resistance unit comprised of miners, managers, doctors and teachers. "At the time, no one took us seriously," he says in an interview, "to many, we were just terrorists. Now, everyone is suddenly interested in us."

He began with $10,000 of his own money and a small group of friends. The unit first gathered information about the enemy. "We brought the Russian soldiers beer and cigarettes, thanked them for their protection, and scouted them in the process," he says. Ironically, it was the occupiers who handed them their first weapons – for their supposed loyalty. They then bought additional weapons from corrupt separatists. The group attacked military camps and individual soldiers who happened to be in places like pubs or saunas. They blew up railroad tracks, transmission towers, power lines and, on several occasions, a gas pipeline running through the area.

They gathered the explosives necessary from private contacts. "Khrustalnyi is a mining town," says Zhemchugov. "I knew how to make bombs even as a child." He and his fellow fighters didn't sign contracts with the Ukrainian military until after eight months, thus becoming agents.

He says he planned and executed 30 successful actions until he kicked the trip wire of a mine during an operation on Sept. 28, 2015. Russian soldiers found him badly injured. He was blinded and doctors had to amputate both of his hands. He was held as a prisoner for around a year and was interrogated and tortured numerous times. He was ultimately released as part of a prisoner exchange. Then-Ukrainian President Petro Poroshenko awarded him the country's highest honor: Hero of Ukraine.

Wear Inconspicuous Clothing and Always Remain Calm

Zhechemchugov has since learned to live with prostheses, and doctors in Cologne, Germany, later succeeded in restoring sight in one eye and removing shrapnel from several parts of his body. He shows what he now does to make himself useful on his smartphone. Under the hashtag #ResistanceMovement, he explains in a YouTube broadcast on the Ukrainian Military Television channel, for example, how to put Russian trucks out of operation (by putting sand in the tank). He also writes rules of conduct for partisan fighters: wear inconspicuous clothing and always remain calm, no matter what.

Several Ukrainian security agencies are responsible for resistance activities, including the military intelligence service (HUR) and the special operations forces (SSO). Individual resistance groups such as Yellow Ribbon or the Berdyansk Partisan Army provide information via Facebook, Instagram, YouTube and the messenger service Telegram — as well as collecting information themselves.

According to one SSO employee, only five to 10 percent of those involved communicate at all with Ukrainian agencies. Others resist by closing their stores when Russian soldiers approach, or by distributing leaflets threatening Russians and collaborators with death. Resistance also includes placing bounties on collaborators or refusing to issue Russian passports, thereby preventing announced referendums in the occupied territories.

A kindergarten teacher from Kherson shares how people there are following strict rules in their daily lives. "We only speak about the resistance in our closest circle," she says. The daycare worker regularly telephones with her son, who lives abroad in Europe, and has a network of contacts in Kherson.

Her son confirms her account during a phone call over an encrypted connection. "When I receive information, I immediately pass it on to a friend in the Ukrainian army," he says. "He then passes it on to the intelligence service." He also carries out research assignments. "Sometimes they ask for specific information, and then I call around until I have it."

He recalls how a shipment of Russian tanks arrived in Kherson. He reported it and they were destroyed a short time later by Ukrainian artillery. A special forces official confirms that reports from citizens on the ground "are as important in target selection as, say, satellite imagery."

The occupiers are aware of just how great the danger from the resistance is. In Kherson, they are now taking increasingly brutal action against the partisan fighters. They have reinforced their checkpoints and intensified the manhunt since a precisely executed air strike against their command center in the city center in early July. "They've been panicking for a while," says Max, a 20-year-old designer who fled the area a month ago and will only provide his first name out of fear for family members who still live in the region. According to public figures, 600 people have already been arrested, an activist says. "But there are probably many more."

There is talk of lists containing the names of former security forces, politicians and normal citizens. Quite a few of them are still missing or were recovered dead after being picked up by Russian troops.

At the beginning of the occupation, Max launched a Telegram group with friends. It soon grew to 5,000 members. "We then set up a new chat, which we monitored closely," he says. "We vetted new members using their social media accounts and asking specific questions." The friends gathered information about Russian troops in their Telegram group, called "Kherson is Ukrainian." "We checked each other's information and then passed it on," he says. They used the Ukrainian e-governance app Diia to identify themselves and then feed information into the chatbot E-Enemy on Telegram, which was specially created by the Ukrainian intelligence service.

"I had my biggest success in March," Max says in an interview held over Zoom. That's when, he says, he discovered a Russian military convoy with trucks, troop carriers, tankers and missile launchers, over 40 vehicles, and passed the information to E-Enemy. "I lay hidden in the grass and saw shells hitting the vehicles," he says. "At first, it made me euphoric, but then I was scared."

Early on, Max had taken part in a protest against the occupiers in Kherson. "Without covering my face." That is one reason his fears began to grow. Ultimately, he found a smuggler to take him out of the city in a minibus for the equivalent of around 150 euros. They reached safe territory after a 12-hour drive. "When I saw our soldiers, it made me cry," Max says. He is now living in Kyiv with acquaintances and hopes that his city will soon be liberated.

These are dangerous times for both the occupiers and the partisan fighters. In the south, citizens have begun preparing for the Ukrainian offensive ordered by President Volodymyr Zelenskyy. A growing number of people are leaving the cities out of fear of imminent street fighting, while others are hoarding food, mixing Molotov cocktails and building bombs.

One locksmith from occupied Enerhodar in the Zaporizhzhia region says he has an entire arsenal in the basement. "But my friends and I will only use these weapons when our troops are close," he says. In the event of a fast-moving offensive, Ukrainian military expert Oleg Zhdanov is hoping for a two-front war for the occupiers. "Then they won't have the capacity to search for the resistance," he says.