American activists inspired by their more radical counterparts in Europe are adopting increasingly aggressive — criminal, even — tactics to protest what they believe to be lack of government action to reduce greenhouse gasses in the name of combating climate change.

American affiliates of a United Kingdom-based group that goes by the name of the Tyre Extinguishers have in the past week been deflating the tires of sport utility vehicles from New York City to San Francisco, leaving behind fliers that read, “Your gas guzzler kills.”

“We have deflated one or more of your tires,” a flier left behind on a vehicle in California read, an example of which is posted on the group’s website. “You’ll be angry, but don’t take it personally. It’s not you, it’s your car.”

Similar incidents have been reported in New York City, Chicago, and Scranton, Pennsylvania. In New York, the group bragged of deflating last week the tires of 40 sport utility vehicles on the Upper West Side of Manhattan.

“The Tyre Extinguishers have disarmed SUVs in New York City for the first time,” the culprits wrote on a website attributed to the group. “We did this because driving around urban areas in your massive vehicle has huge consequences for others. This is a machine that destroys life with terrifying efficiency.”

Another group professing to be acting in the name of a “climate emergency” stopped traffic for more than 90 minutes on the ring road encircling Washington last week by sitting down in the multi-lane roadway with banners reading “Declare Emergency.”

Police arrested 14 members of the group, according to its website, some of whom came from as far away as Florida and Oregon.

Their protest brought traffic on the so-called Beltway to a standstill. One of the motorists trapped in the blockade, a man claiming to be a parolee trying to get to work, was filmed  in a video that later went viral pleading with the protestors to let him through lest he lose his job and be returned to prison.

“Ya’ll are so inconsiderate,” the man can be heard saying on the video recorded by an independent journalist. “One lane — I’m asking — one lane. One lane before I go to prison.”

The protestors ignored him.

Declare Emergency, as it is known, claims ties to an international network of climate change activists, with members across Europe, Canada, and Australia promising an “unprecedented level of nonviolent disruption to halt the climate and ecological emergency.”

A member of the group, Deborah Kushner of Staunton, Virginia, said, “The world’s lack of any significant action to prevent the ravages of the impending climate catastrophe is what has led me to take this action. … disaster is here, and worsening by the day. I choose to not be complicit in the horrible death of this amazing planet. We are far into the 11th hour. It’s time for us all to rise.”

The group says President Biden has failed to live up to his promises to combat climate change. They want him to declare a “climate state of emergency” and enact what it calls a “World War II-type” mobilization to reduce emissions and curb the use of fossil fuels.

The tactics now being used by American activists mirror those of protestors in Europe, who have taken increasingly aggressive tactics in recent years. Activists have blocked highways and access roads to oil terminals, vandalized gas pumps, and even glued themselves to airplanes and paintings at the Royal Academy in London in the name of fighting climate change.

Authorities in the U.K. have attempted to amend the laws there to ban the tactic — called “locking on” — by criminalizing the obstruction of infrastructure and transport networks, but the efforts have met resistance from opposition Labour Party parliamentarians who professed concern about restrictions on the rights of free speech and protest.