“The network of feminist organisations in our country is a breeding ground for extremist actions,” said MP Oleg Matveichev of the ruling United Russia party, announcing a draft law that would recognise feminism as an “extremist ideology.”
The case of Darya Trepova, on trial for terror offences for her alleged part in the bombing, has unleashed a wave of hostility towards female activists led by politicians and state media.
Feminist activists have reported an uptick in abuse and threats, with personal details posted online, as nationalists hunt for accomplices of Ms Trepova, said to have been an anti-war radical.
Members of feminist groups, such as the popular Feminist Anti-War Resistance (Far) network, fear proscription.
“There have been many absurd proposals lately, even by the standards of the regime,” says Maria, a Russian human rights activist associated with the network of jailed dissident Alexei Navalny, who gives only a first name.
“I am more than sure that sooner or later they will ban Far and similar feminist activist groups,” she added.
Feminist campaigners have previously said that chauvinist attitudes within the Russian state gave them greater scope for dissent and opposition to the war as they were taken less seriously, while other activist groups were crushed.
That tolerance no longer exists, according to one Far activist, who says that 16 feminist campaigners are now on trial for anti-war offences such as discrediting the army, which were introduced shortly after the invasion of Ukraine.
Female activists such Alexander Skochilenko, jailed for placing anti-war messages on supermarket price tags, have reportedly faced torture in prison.
While legislating against feminism might seem impractical, it could have wide-ranging effects, suggests lawyer Anastasia Burakova.
“A prosecutor or court can recognise one organisation as ‘extremist’,” she says. “Law enforcement can then use the formal status… as a pretext for increasing repression against other opposition groups.”
The regime can use supposedly-independent experts to “formally substantiate connections between random people they want to persecute” and designated organisations.
Russia’s secret services will be under pressure to deliver results after the security breach of the St Petersburg bombing, says political analyst Antonin Barbashin, head of online news journal Riddle.
“There are people being blamed for this,” he told i. “They will need to produce something useful.”
Feminist groups have become a “natural enemy” for the regime, said Mr Barbashin, as they have become rallying points for anti-war sentiment, and also espouse liberal values that jar with the traditional conservative ideology of the Kremlin.
The regime is likely to recognise the bombing as an opportunity to strengthen its grip on society, he believes.
“Based on previous experience, they will use it as a pretext to solve problems with internal enemies,” says Mr Barbashin.
Pressure on dissidents is likely to increase across the spectrum, analysts believe, as arrests and prosecutions tick up. More than 500 activists have faced criminal charges for anti-war offences, according to Russian human rights group OVD-Info.
The targets of the upcoming offensive are not limited to feminists. Russian officials have also accused the network of jailed dissident Mr Navalny of involvement with the bombing.
The network is sufficiently concerned to have issued a memo this week offering staff support for asylum claims if they wish to flee the country, due to “the added risk of being labelled as terrorists”.
Many of the campaigners who have resisted throughout the war are unwilling to give up now. But there are no illusions that they will face an increasingly hostile environment.