President Trump’s executive order on immigration is an assault on Europe’s interests and values. It condemns entire nations and prevents refugees who have committed no crime from finding safety, making an international response to the refugee crisis all the harder. It also risks setting back co-operation on terrorism while stimulating Isis’s recruitment. We call on the European leaders in Malta to respond in three ways:

• The EU should speak with one voice in defence of international agreements and basic human rights, including the right of refuge. Seeking special deals on a country-by-country basis will simply weaken everyone.

• The EU should launch a rule-of-law mission to assist EU citizens in US ports and airports. The EEAS and the member states should coordinate efforts in Washington, in order to offer the best consular protection to European citizens possible. Dual citizens should not be discriminated on the basis of their second passport.

• The isolationist policies of our transatlantic neighbour should drive European nations closer together in sharing intelligence within the EU in order to enhance protection against terrorist threats. It is high time to think about European security, both internally and externally, in a more consolidated and responsible fashion.

Europe’s place in the world is under threat from power politics, closed borders and closing societies. European leaders should not stand by as international agreements aimed at protecting the weak, the vulnerable, and those fleeing war and torture are invalidated by late night executive orders.

Mark Leonard Director, European Council on Foreign Relations

Carl Bildt Former prime minister of Sweden

Alexander Stubb Former prime minister of Finland

John Bruton Former taoiseach of Ireland

Pascal Lamy Former director-general of the WTO; former EU commissioner

Javier Solana Former secretary general of Nato

Wolfgang Schüssel Former chancellor of Austria

George Papandreou Former prime minister of Greece

Gordon Bajnai Former prime minister of Hungary

Hans Eichel Former finance minister of Germany

Lykke Friis Former minister for climate, energy and gender equality, Denmark

Andrzej Olechowski Former foreign minister of Poland

Connie Hedegaard Former European commissioner for climate action

Martin Lidegaard Former foreign minister of Denmark

Baroness Janet Royall Former leader of the opposition in the UK House of Lords

Adam D Rotfeld Former foreign minister of Poland; Co-chairman of Polish-Russian Group on Difficult Matters; Commissioner of Euro-Atlantic Security Initiative

Gunilla Carlsson Former international development cooperation minister of Sweden

Joaquín Almunia Former vice-president of the European commission

Tibor Dessewffy President, Demos Hungary

Karin Forseke Chairman, Alliance Trust Plc

Carlos Gaspar Member of the board of directors, Portuguese Institute of International Relations (IPRI)

Sylvie Goulard Member of the European parliament

Marietje Schaake Member of the European parliament

Teresa Gouveia Trustee to the board of the Calouste Gulbenkian Foundation; former foreign minister of Portugal

Sandra Kalniete Former foreign minister of Latvia; Member of the European parliament

Roderich Kiesewetter CDU special representative for foreign affairs

Heather Grabbe Executive director, Open Society Policy Institute

Ulrike Guérot Senior associate for Germany, Open Society Initiative for Europe

Bassma Kodmani Executive director, Arab Reform Initiative

David Koranyi Director, Energy Diplomacy Initiative, Global Energy Center, The Atlantic Council

Brigid Laffan Director of the Robert Schuman Centre for Advanced Studies and Global Governance Programme, European University Institute

Sonja Licht President, Belgrade Fund for Political Excellence

Irene Lozano Writer; former member of the Congress of Deputies

Miguel Maduro Professor and director, Global Governance Programme at the European University Institute; former minister

Kalypso Nicolaïdis Professor of international relations, University of Oxford

Christine Ockrent Commentator and writer; Presenter of Affaires Internationales, France Culture Radio

Dick Oosting Former CEO, European Council on Foreign Relations

Behlul Ozkan Assistant professor, Marmara University

Žaneta Ozoliņa Professor, University of Latvia; former director, Latvian Centre for Human Rights

Lapo Pistelli Senior vice-president, stakeholder relations for business development support, ENI; former deputy foreign minister of Italy

Albert Rohan Austrian ambassador (retired)

Daniel Sachs CEO, Proventus

Aleksander Smolar Chairman of the board, Stefan Batory Foundation

Ion Sturza Founder and chairman, Fribourg Capital; former prime minister of Moldova

Hannes Swoboda Former president, Progressive Alliance of Socialists and Democrats, European parliament

Anna Terrón Special adviser to the European commissioner for trade; President, InStrategies

Nathalie Tocci Deputy director, Istituto Affari Internazionali

Jose Ignacio Torreblanca Editorial director, El País

Erkki Tuomioja Former foreign minister of Finland

Ivan Vejvoda Director, Europe Project, Institute for Human Sciences

Antonio Vitorino Lawyer; former EU commissioner

André Wilkens Publisher and author

• Join the debate – email guardian.letters@theguardian.com

• Read more Guardian letters – click here to visit gu.com/letters