Washington(CNN) US officials say a trio of assassination attempts targeting pro-Russian officials over the past two weeks suggests a burgeoning resistance movement against pro-Russian authorities occupying parts of southern Ukraine.
While it is just a few incidents isolated to the town of Kherson so far, US officials say the resistance could grow into a wider counterinsurgency that would pose a significant challenge to Russia's ability to control newly captured territory across Ukraine.
The Kremlin "faces rising partisan activity in southern Ukraine," Avril Haines, the director of national intelligence, said during a conference in Washington, DC, on Wednesday.
The US believes that Russia does not have enough forces in Kherson to effectively occupy and control the region, one US official said, especially after pulling forces from the area for the fight to the east in Donbas. Another US official told CNN that move may have provided Ukrainian partisans with a window in which to attack locally installed Russian officials.
Ukraine has also conducted limited counterattacks near Kherson, further straining Russian forces.
The region is critical to Russia's hold on Ukraine's Black Sea coast and controls access to the Crimean peninsula. It's unclear how many Russian forces are in or near Kherson, but an occupation against a hostile local population requires far more soldiers than a peaceful occupation of territory.
Russia's leaders have prioritized the military campaign at the expense of any semblance of government. "It's clearly not something they're able to invest in right now," one US official said.
The first attack in Kherson occurred on June 16, when an explosion shattered the windows of a white Audi Q7 SUV. The vehicle was left seriously damaged, but the target of the attack survived.
Eugeniy Sobolev, the pro-Russian head of the prison service in occupied Kherson, was hospitalized after the attack, according to Russian state news agency RIA Novosti.
Less than a week later, a second pro-Russian official in Kherson was targeted. This time, the attack succeeded. On June 24, Dmitry Savluchenko, the pro-Russian official in charge of the Department of Youth and Sports for the Kherson region, was killed, RIA Novosti reported. Serhii Khlan, an adviser to the head of the Ukrainian Kherson Civil Military administration, called Savluchenko a "traitor" and said he had been blown up in his car. Khlan proclaimed, "Our partisans have another victory."
On Tuesday, the car of a third pro-Russian official was set on fire in Kherson, according to Russian state news agency Tass, though the official was not injured. It's unclear who committed the attacks.
There does not appear to be a central command guiding an organized resistance, officials said, but the attacks have increased in frequency, particularly in the Kherson region, which Russia occupied in March at the beginning of its invasion.
A source familiar with Western intelligence was more skeptical about whether the resistance could develop from partisan attacks to a more organized campaign capable of managing the attacks and supplying weapons and instructions
So far, the resistance has not dented Russia's control over Kherson, the source familiar with Western intelligence emphasized.
But in the long term, the US assesses that Russia will eventually face a counterinsurgency from the local Ukrainian population.
"I think Russia is going to have significant challenges in trying to establish any sort of stable administration for these regions, because likely collaborators -- more prominent ones -- are going to be assassinated and others will be living in fear," said Michael Kofman, director for Russia studies at the Center for Naval Analyses, a Washington-based think tank.
On Tuesday, Russian-appointed authorities in the Kherson region arrested the elected Ukrainian mayor of the city, Ihor Kolykhaiev, hours before announcing plans for a referendum to join Russia. The pro-Russian military-civilian administration accused Kolykhaiev of encouraging people to "believe in the return of neo-Nazism."
Kolykhaeiv's adviser said Russian authorities also had seized hard drives from computers, ransacked safes and searched for documents. Earlier this month, Ukraine's military said "invaders" had broken into Kherson State University and abducted the rector.
Russian forces have gradually instituted the ruble as the local currency and issued Russian passports.
In Mariupol, pro-Russian authorities celebrated the so-called "liberation" of the city in May. The Russian-aligned Donetsk People's Republic changed road signs from Ukrainian to Russian and installed a statue of an elderly woman grasping a Soviet flag. Meanwhile, the iconic Mariupol sign painted in Ukrainian colors was repainted in Russian colors.
Despite Russia's efforts to eliminate Ukrainian history, ethnicity and nationalism from Kherson and other occupied territories, the Ukrainian population shows a willingness to resist.
"The occupiers and local collaborators are making more and more loud statements about [the] Kherson region joining Russia," a Ukrainian official said last week, "but every day, more and more Ukrainian flags and inscriptions appear in the city."
The attempts to forcibly erase Ukrainian culture and dictate a Russian hegemony have produced the opposite effect in some cases, according to a senior NATO official.
"There have been reports of assassination attempts against some of the quislings that have been put in place to be governors, mayors [and] business leaders," said the NATO official. A quisling is a traitor who collaborates with an enemy force, named after a Norwegian official in World War II who collaborated with the Nazis. "That almost certainly has deterred Russian sympathizers or Russians or whoever they're going to bring in there to take these posts from taking them up in the first place."
As an occupying force in Kherson -- in particular, one that seems intent on maintaining control -- Russia has to provide basic services in the territories it manages, like clean water and trash pickup. But the US assesses that acts of resistances are making it difficult to provide governance and basic services, one of the US officials said.
The US knew there was a "serious resistance network" within Ukraine that would be able to take over if and when the military had failed, the official said. Before the invasion, the US anticipated the insurgency would emerge, coupled with guerrilla warfare, after a brief period of intense fighting in which Russia prevailed. But the war has now dragged on for months, with many analysts predicting a far lengthier conflict.
A senior US official warned a Russian counterpart before the conflict that they would face an insurgency if they invaded Ukraine and tried to occupy territory, the official said. But the warning fell on deaf ears and the invasion proceeded, driven in part by hubris and bad intelligence.
Russia believed its forces would be greeted with open arms and would crush any resistance quickly, erroneous fantasies that fell apart quickly but did little to change Russian President Vladimir Putin's calculations.
Kofman says it's unclear what type of governing framework Russia will try to create to exert control, but there is no doubt that it intends to retain the territories. After facing prolonged, bloody insurgencies in Afghanistan and Chechnya, the Kremlin knew to anticipate another potential insurgency in Ukraine.
"They did see it coming," Kofman said. "That's why they set up filtration camps and shipped out a lot of the population out of occupied areas."