British politicians and arms control advocates are calling for the United Kingdom to stop selling tear gas, rubber bullets, and other riot control equipment to law enforcement in the United States in response to police brutality during Black Lives Matter protests.

More than 160 members of Parliament from across the UK’s politics, including from Prime Minister Boris Johnson’s Conservative Party, signed a letter to British trade secretary Liz Truss asking their government to stop the export of policing and security equipment to the US.

“The brutality now aimed towards protesters and reporters across the country is unacceptable,” the letter read.

According to the Independent, the US is a major customer of UK-made weapons: “Government export license records show that the US is one of the world’s largest buyers of UK arms, with almost £6 billion worth licensed for export since 2010.”

Activists said that although it’s unclear how likely it is the measure will be adopted, the letter was an important step toward curbing human rights abuses.

“I think condemning police violence is one thing, but if you are supporting that violence there is a real hypocrisy,” Andrew Smith of the Campaign Against Arms Trade in London told BuzzFeed News. Along with other campaigners, he began calling on the UK government to stop those weapons sales in early June.

“The real value of this is a symbolic political value,” Smith added. “It sends an important message and sets an important precedent.”

Although the UK Parliament has yet to debate the measure, the campaign has had victories. Last week, the Scottish Parliament voted 52 to 0, with 11 abstentions, to “immediately suspend all export licenses for tear gas, rubber bullets and riot gear to the US.”

There’s precedent for the move — last June, the UK’s government suspended exports of tear gas and riot control equipment to Hong Kong until concerns over human rights abuses against protesters were addressed.

In 2013, the UK halted export licenses of some weapon parts to Egypt in response to reports that security forces had used excessive force against protesters there.

The movement in the UK, which since the 1980s has rarely used tear gas, coincides with a campaign from Democratic lawmakers in the US to ban the use of tear gas. Although law enforcement in places including the US, Canada, Brazil, and Bahrain have used it during demonstrations, the 1993 International Chemical Weapons Convention bans its use in war. The US has both signed and ratified that treaty, which does not apply to domestic uses.

“The egregious mistreatment of peaceful protesters by law enforcement in our country has been reprehensible. It’s a shame that other countries have taken notice of these anti-democratic activities and feel the need to take action,” Rep. Mark Takano, who co-sponsored the anti-tear gas bill along with Rep. Alexandria Ocasio-Cortez and Rep. Chuy Garcia, told BuzzFeed News. “I support any efforts to demilitarize our police forces.”

The US has faced increasing international censure over police brutality. Last month, the UN High Commissioner for Human Rights called on authorities in the US to take “serious action to stop such killings.”

Philip McHarris, a doctoral candidate at Yale whose work focuses on race and policing, told BuzzFeed News that since the early 1900s, police departments in the US have adopted not only military equipment, but also tactics and strategies.

“There are pathways through countries like the UK that are facilitating the militarization of the police in the US, and we see what the outcomes are,” McHarris said. “People are being brutalized in the street, even killed in their own homes because this equipment is fueling it.”