Just two months ago the whole world celebrated Islamic State’s defeat as a military force. That victory was led by the women of the YPJ (women’s protection units), along with the other Kurds, Arabs and Christians of north-east Syria – the democratic, female-led, autonomous region more commonly known as Rojava.

The Kurds and their allies were joined by British heroes like Anna Campbell, who was killed by the Turkish air force while fighting jihadi ground forces in Afrin. Seven other British people lost their lives volunteering with the YPG (people’s protection units) and YPJ in the fight against Isis and jihadi terrorism.

But now Sajid Javid has issued British citizens volunteering in Rojava with an ultimatum – leave within a month, or face a 10-year jail sentence if they try to return to the UK.

Under a new anti-terror law, the home secretary can designate any area of the world as a no-go zone for British citizens, and Rojava is first on the list. Javid has decided that simply travelling to or remaining in Rojava should be considered a terrorist act – even though the UK is part of the international coalition against Isis, which relied on Rojava throughout its campaign.

Theresa May said the military defeat of Isis “wouldn’t have been possible without the immense courage of … our allies”. She could only claim credit for Isis’s defeat because of the sacrifices of Kurdish and Arabic communities on the ground in Rojava, who lost more than 10,000 of their sons and daughters in the war against Isis. They proved themselves the world’s most trusted partners in the fight against terrorism.

Yet using a law supposedly created to defend against Isis, Javid is criminalising as “terrorists” those who have given more than any other British citizens in this struggle.

You have never honoured the bravery and sacrifice of volunteers in Rojava – you even refused to help bring back Anna Campbell’s body from Afrin.

Instead, you have been keeping up lucrative arms sales and trade deals with the Turkish state that killed her, while trying to imprison British volunteers who have joined the anti-Isis struggle by any means possible.

Rojava has played host to British MPs and US senators, to politicians and world-leading academics, to hundreds of journalists from all over the world. They have witnessed how women are experiencing newfound freedom and equality, and how different ethnic minorities are able to speak their own language, practise their own customs, and live together in peace – all things which were impossible under the Syrian regime.

Even British volunteers working in the civilian sector in Rojava now face an automatic 10-year jail sentence: this means people who have come here to learn, share and offer their support in the medical field, reforestation projects and ecological initiatives, or the autonomous women’s village Jinwar.

All these projects contribute to the establishment of a new, secular, gender-liberated way of life here in Rojava. In fact, if Isis’s ideology is to be truly eradicated, it will be through these principles as they flourish and spread in society. Far from being an Isis stronghold, Rojava is a beacon of women’s resistance against the oppressive jihadist mentality, and a grassroots, direct-democratic alternative to the brutal regimes which rule elsewhere in the Middle East.

Throwing people in jail for 10 years just for being in a particular physical location is a serious abuse of civil liberties, whoever the targets are. Worse, you’re using this power to target people who have come to support the only movement which stands a chance of defeating Isis in the region.

As current and former British and international volunteers in Rojava, as the family members of those who have died in Rojava, as supporters of human rights, we urge you to scrap this law.

But those of us still in Rojava would also like to make you an offer: follow in the footsteps of your parliamentary colleagues Lloyd Russell-Moyle MP and Lord Glasman, and come and visit us in north-east Syria.

Here, you will be able to meet the people who have done more than any others on the face of the planet to defeat Isis, their rule of terror, and everything they stand for. You will find Kurdish women who stood up against terrorism when the world looked away, and British people who have made the brave decision to come and join their struggle.

If you really want to defeat Isis’s patriarchal, murderous ideology, you have our full support. But you’d be better off coming here and speaking to the Kurds and other local people who actually fought and defeated Isis – not throwing their British friends and supporters into jail for the “crime” of fighting for a better world.

Families of those killed in Rojava

Dirk and Sofia Campbell, father and sister of Anna Campbell, UK volunteer who died fighting Turkish occupation of Afrin

Vasliki and Chris Scurfield, parents of Kostas Scurfield, UK volunteer who died fighting Isis with YPG

Jane Lyndon, mother of Ollie Hall, UK volunteer who died fighting Isis with YPG

Angie Blannin, mother of Jac Holmes, UK volunteer who died fighting Isis with YPG

International volunteers:

Macer Gifford, former UK volunteer in Rojava, fought Isis with YPG and MFS

Josh Walker, former UK volunteer in Rojava, fought Isis with YPG

Dan Newey, former UK volunteer in Rojava, fought Isis with YPG

Steve Kerr, former UK volunteer in Rojava, fought Isis with YPG and SDF

Jim Matthews, former UK volunteer in Rojava, fought Isis with YPG

Seweryn Mazur, former UK/Polish volunteer in Rojava, fought Isis with YPG and SDF

Joshua Bailey, former UK volunteer in Rojava, fought Isis with YPG

Ozkan Ozdil, former UK volunteer in Rojava, combat medic with YBT

Stefan Bertram-Lee, former UK volunteer in Rojava, joined YPG and DKP

Vienne Zielinska, Polish UK resident and volunteer in Rojava, ecologist

Connor Mason, current UK volunteer in Rojava, aid worker

Tanja Baldock, current UK volunteer in Rojava, civil volunteer

Matt Broomfield, current UK volunteer in Rojava, journalist

Michael Chant, current UK volunteer in Rojava, video journalist

Danielle Loader, current UK volunteer in Rojava, engineer

Joshua Molloy, former Irish volunteer in Rojava, fought Isis with YPG

Lucas Chapman, current US volunteer in Rojava, fought Isis with YPG

Matthew Margala, current US volunteer in Rojava, joined YPG

Michael Paul Maldonado, current US volunteer in Rojava, fought Isis with YPG

Kyle Town, current Canadian volunteer in Rojava, fought Isis with YPG

Leopoldo Odelli, current Italian volunteer in Rojava, joined YPG

Corey Wetherholt, current American volunteer in Rojava, joined YPG

Guillaume Auger, former Canadian volunteer in Rojava, fought Isis with YPG

Vaclav Skutil, former Czech volunteer in Rojava, fought Isis with YPG

Tommy Mørck, former Danish volunteer in Rojava, fought Isis with YPG

Maxime Barrat, former French volunteer in Rojava and Shengal, fought Isis with YPG and YBŞ

Erik Bouchet, former French volunteer in Rojava, fought Isis with YPG

Jan Kolbe, current German volunteer in Rojava, Internationalist Commune of Rojava

Milo Marcks, current German volunteer in Rojava, Internationalist Commune of Rojava

Jan Lukas Kuhley, current German volunteer in Rojava, fought Isis with YPG

Maria Edgarda Marcucci, former Italian volunteer in Rojava, fought Turkish occupation of Afrin with YPJ

Warren Stoddard, former US volunteer in Rojava, fought Isis with YPG

Hunter Pugh, former American volunteer in Rojava, fought Isis with YPG

Claudio Locatelli, former Italian volunteer in Rojava, fought Isis with YPG

Alessandro de Ponti, former Italian volunteer in Rojava, fought Isis with YPG

Matteo Caruso, Italy, former Italian volunteer in Rojava, fought Isis with YPG

Gaetano Napoli, Italy, former Italian volunteer in Rojava, fought Isis with YPG

Emanuele Martuscelli, former Italian volunteer in Rojava, fought Isis with YPG

Jacopo Bindi, former Italian volunteer in Rojava

Ivan Borodon, current Russian volunteer in Rojava, joined YPG

Supporters:

Noam Chomsky, academic

Lloyd Russell-Moyle MP, Labour

Kevin Blowe, coordinator, Network for Police Monitoring (Netpol)

Peter Tatchell, human rights defender

Caroline Lucas MP, Green party

David Graeber, academic

Kurdistan Solidarity Network

Kurdistan Solidarity Network Bristol

Campaign Against the Criminalisation of Communities

Andrew Feinstein, Corruption Watch UK, former member of the National Assembly of South Africa

Les Levidow, Open University

Raj Chada, lawyer at Hodge Jones and Allen, former leader of Camden Council

Dr Jonathan Oppenheim, University College London

Dr Elly Robson, Jesus College, University of Cambridge