An international neo-Nazi terrorist group with origins in the US appears to be quickly rebuilding its global and stateside ranks, according to information obtained by the Guardian from its digital accounts.

Founded in 2018, the Base has been the intense focus of a years-long FBI counter-terrorism investigation that has resulted in more than a dozen of its members arrested. It has plotted an assassination, mass shootings and other actions in Europe, which made it a proscribed terrorist organization in several countries.

By 2022, it seemed to disappear. Yet its founder and leader, Rinaldo Nazzaro, a former US special forces contractor residing in Russia, used the safety of Russian apps before the November election to recruit and reorganize during a tense political moment. At one point, he even solicited ex-American soldiers with an offer of $1,200 a month to put members through paramilitary training somewhere in the Pacific north-west.

The Base’s regrouping comes at a time when the Trump administration has made it a policy goal to move away from policing far-right extremism and during the appointment of Kash Patel – a Maga acolyte who lauds January 6 attackers and has peddled Qanon conspiracy theories – to helm the FBI. Experts say federal law enforcement ignoring far-right groups such as the Base could expose Americans to increased domestic terror threats.

Nazzaro’s efforts, so far, appear to be paying off: the Guardian was tipped to an audio message released in mid-February from an assumed new leader of the Base with an American accent, discussing the ambitious future of the group.

After criticizing other neo-Nazi organizations such as Blood Tribe for publicly protesting against drag-queen story hours in the midwest, the voice preached covert action and quiet preparations for armed cells throughout the US rather than flashy activism.

“Are we just going to be reactionary? Or are we going to be part of the solution? The military solution,” they said. “Because inevitably we’re going to end up in some sort of military situation, what are the choices?”

The voice then describes a “black scenario” where the US government soon collapses and there’s a need to “provide for your family” and for “white women”.

“There is no political solution, only a military solution,” they can be heard saying under heavy voice modulation. “So act accordingly.”

A flurry of new images on the Base’s various social media accounts, some closed and some open, show members claiming to be in the US and across Europe brandishing pistols or military-style rifles and donning the trademark skull mask of the accelerationist neo-Nazi movement – one that demands acts of terrorism to bring down world governments.

In one photo, a member is holding a knife and what appears to be a pistol in front of the Base flag in the United Kingdom, while others feature members in Bulgaria, Italy, Belgium and Sweden. Last week, on the Base’s VKontakte account, it released a video showing a masked man purportedly in Bulgaria firing a pistol three times into the air with the group’s signature black flag beside him.

Real arrests show the multimedia posts aren’t a case of digital bluffing. In recent months, authorities in the Netherlands and Italy have carried out multiple arrests of suspected members on terrorism-related charges.

“The extreme rightwing terrorist organization the Base was proscribed in the UK since July 2021,” said a spokesperson for the Home Office, the department overseeing British security agencies, adding that being a member of the Base “carries a maximum penalty of 14 years in prison”.

Steven Rai, an analyst at the Institute for Strategic Dialogue (ISD), has also noticed the Base’s increased activities online.

“The Base has released a slow but steady trickle of propaganda over the past several months that has mostly highlighted their presence in Europe, so this shift in focus towards the US should raise alarms,” said Rai.

“The timing of this shift is particularly noteworthy – while neo-Nazi accelerationist groups like the Base have been on their back foot due to intense law enforcement pressure, which disrupted their most integral organizers and propaganda artists, they may sense an opening with the recent change of administration in the US.”

On the day of Trump’s inauguration, in a kind of taunt to authorities, the Base released a photo of the largest number of American members in one photo in over a year, two of them holding guns. The Base also solicited donations to a Bitcoin wallet, asking for money for weapons and ammunition. Shortly after, it thanked supporters for donations, then proudly displayed blanks they will put “to good use” and use to “train in small unit tactics”.

The FBI declined to comment on whether it will prioritize investigations into the Base or other far-right extremists in the future.

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Both Trump and Patel have promised “major, major” reforms of the bureau, spurring an internal war between agents and the White House, with combating far-right extremism believed to be low on the list of priorities. But the Base also acknowledged the threat of law enforcement and released a new oath for American members, which included requirements to have a personal AR-15 rifle and nine 30-round magazines of ammunition.

“I willingly accept the risk of being targeted by law enforcement as a result of my membership in the Base to include being placed on government watchlists,” reads part of that oath. “However, if questioned by law enforcement, I will say nothing.”

Colin Clarke, a terrorism expert and director of research at the Soufan Center, believes the far right has sensed their window of opportunity.

“I think groups like the Base, far-right extremist groups that are strategic, have been waiting for the right opportunity before reinvigorating their respective organizations,” he said, adding that it’s expected that Patel will direct counter-terrorism assets towards leftwing organizations. “This means that far-right extremist groups likely perceive the re-election of Trump as a green light to rebuild without fear of arrest or prosecution.”

Rai concurred: “Violent extremists are absolutely paying attention to the changes in the national security establishment in the US.”

Contacted via encrypted text, Nazzaro would not answer if the audio message was the voice of a new leader that he hired to be his proxy in the US. He did mention that the Base supports neither Republicans or Democrats and that Trump’s presidency is irrelevant to his movement.

“At worst, it gives false hope by perpetuating the erroneous notion that a political solution is possible,” he said.

Suspicions have surrounded Nazzaro and his connections to Russian intelligence agencies. Living now as a semi-defected American in Saint Petersburg, his work with US special forces during the war on terror meant he had a top secret clearance while fighting insurgencies in Iraq and Afghanistan. But only a few years after that work, he would found a neo-Nazi terrorist group of his own that sees the US government as the enemy.

Nazzaro has denied any and all links to the Kremlin, once telling Russian state television that he has “never had any contact with any Russian security services”.

Clarke is skeptical and said that Nazzaro’s presence in Russia means “Russian intelligence services will inevitably wield influence over the Base and could be orchestrating some of the organization’s next moves, especially in terms of recruitment and propaganda”.

Western intelligence agencies are constantly warning that the Kremlin is seeking to destabilize Nato member states, including supporting violent, far-right organizations in Europe. Late last year, Ken McCallum, the head of MI5, said that Russia was using “arson, sabotage” and other “actions conducted with increasing recklessness” on European and British soil.