Russian activists and journalists speaking out against their country's so-called "special military operation" in Ukraine have had their homes vandalised by unknown pro-Kremlin figures.

Apartment doors have been daubed with threatening graffiti labelling the people inside a "traitor", with messages featuring the letter "Z" - a pro-Kremlin symbol of Russia's war in Ukraine.

Other examples are even more extreme. In one case, a leading Russian journalist discovered a pig's head wearing a wig on his doorstep with an anti-Semitic sticker stuck to his door.

Alexei Venediktov, the long-time editor of radio station Ekho of Moscow before it stopped broadcasting due to increased Russian censorship, posted photos of the vandalism, pointing out the irony of an anti-Semitic attack happening in the "country that defeated fascism".

Such vandalism is a sign of the increasingly intimidating atmosphere in Russia for those people who publicly express their opposition to the war in Ukraine.

When Darya Kheikinen looked through the peephole on the door of her St Petersburg apartment, she noticed it had been painted red on the outside.

She guessed straight away what had happened - there had been similar instances with other activists.

She opened the door to find the word "traitor" scrawled in large red letters across the outside, several pieces of paper with messages such as "a traitor to the motherland lives here" pinned to her home, and a pile of manure on the mat at her feet.

"It probably happened because of my public anti-war statements and opposition views," Ms Kheikinen, a well-known political activist, told the BBC, adding that the same thing happened to three other St Petersburg activists at the same time.

It happened again the next morning - but only to her this time.

"The door was covered in green dye, and there was spray foam in the lock. There were signs reading 'we will not forgive Nazism' and 'a Finnish Nazi lives here'," she said, pointing out that her surname is Finnish.

The messages reflect the Kremlin's false claims that Ukraine's government is run by Nazis and its operation in Ukraine is necessary to "denazify" the country.

Ms Kheikinen doesn't know who was responsible for the attack, but said as far as she knows the only people who have her address are her parents and the police.

"I can't say that it has scared me," she said. "Actually, I find it amusing. Imagine some idiot dragging a bag of manure up the stairs to the 11th floor - and doing it two nights in a row!"

Since Russia's war in Ukraine began, life for those who oppose it has become increasingly difficult. The government passed a law threatening people who spread "fake" information about the war with 15 years in prison.

Vladimir Putin and other politicians have painted any opposition to the war as a betrayal of the country.

"Any people, and especially the Russian people, will always be able to distinguish the true patriots from the scum and the traitors, and just spit them out like a fly that accidentally flew into their mouth," the president said in a speech on 16 March.

He went on to claim that the West is trying to destroy Russia by using "fifth columnists" - meaning enemies within - to provoke civil confrontation.

Just a few hours after that speech, student activist Dmitry Ivanov, whose anti-war opinions are a major feature of his Telegram channel with nearly 10,000 followers, received a call from his mother asking if he had seen the graffiti all over the door to their landing.

"It said, 'don't betray the motherland, Dima'," he told the BBC. There were also three large "Z"s, making it clear the message related to Russia's actions in Ukraine.

"The neighbours probably weren't that surprised", he said, explaining that his political opinions are no secret because the police turn up at his door every now and then to warn him against attending protests.

The doors of three other activists and journalists in Moscow were also vandalised that evening.

But Mr Ivanov, whose activism began by reporting on a protest against a noisy fan-zone directly outside his university during the 2018 football World Cup in Russia, said the attack hasn't put him off.

"The actions of the police frighten me much more. They have the resources and power to ruin people's lives, but this - this is just minor hooliganism."

He decided not to report the vandalism to the police, because he didn't want to end up on the wrong side of them, he said.

Incidents like these might be minor, but they are the product of a political environment where you either support the war or are labelled a traitor.

The consequences for those who oppose Russia's actions in Ukraine are wide-ranging, and can include losing your job or even criminal prosecution.

But Mr Ivanov says that despite the danger, his opposition will continue.

"The threat of 15 years in jail worries me. But the war is much more scary. This completely destructive, senseless cruelty carried out by our country in our name - it is just a huge shock."