As we mark the anniversary of the 1968 Prague Spring — when Warsaw Pact tanks crushed the hopes of a pro-democracy movement — it is tempting to imagine that the era of authoritarian powers has come to an end. That fundamental rights and freedoms are secure in Europe. That its citizens, armed with the memory of the 20th century, would not wish to see brutal governments return. But that would be a mistake.

Fifty years after tanks rolled into Prague, and almost 30 years after the Berlin Wall came down, authoritarianism is back at the heart of the EU, a union founded on the promise of “never again.”

The threat no longer comes from the Brezhnev doctrine — which called on the Soviet Union to intervene when countries appeared to rebel against socialist rule — but it is fed by the same hatred of freedom.

Across the EU, democratically elected governments have set out to dismantle the rights enshrined in the bloc’s founding texts. Hungary and Poland are, of course, at the heart of this “reactionary revolution,” followed closely by Italy and Austria, and the electoral successes of those governments are encouraging other European politicians to follow the same path.

To be sure, comparisons to the 1930s are overblown. But we can ill afford to downplay the threat of increasing attacks on a European project that has been instrumental to keeping the peace.

The ideological offspring of the forces that were defeated in 1945 and 1989 are already in government in several European countries.

Nor should we take for granted the progress made in the past decades. Those who were born “on the wrong side of the Wall” around 1989, that experienced the "Winds of Change" of that era, can take advantage of possibilities their parents could never enjoy as — little by little — rights once denied have become guaranteed by law across a unified Europe.

This was not an easy process, and many have painful memories of that transition. But that does not mean it can’t be reversed.

The ideological offspring of the forces that were defeated in 1945 and 1989 are already in government in several European countries. Europe may once again be torn apart.

As Joschka Fischer said at the anniversary of the signing of the Schuman Declaration in 2000, “a step backwards, even just a standstill or contentment with what has been achieved, would demand a fatal price above all of our people.”

In the 18 years since his speech, anger and resentment against Europe have grown. Many are disappointed, and the EU’s many positive aspects were badly defended, if at all.

We no longer celebrate or understand the fact that the EU brought peace to a continent once ravaged by war, as new conflicts emerge and memories fade. We no longer shout from the rooftops about the economic, social and democratic progress the EU brought to Central and Eastern Europe, where the lives of so many have improved. The memory of dictatorships in the former Warsaw Pact nations has faded to a mere fragment of history.

Europe faces big challenges: Climate change, persisting inequalities, the colossal challenge of migration, which only demagogues believe can be resolved easily. Not to mention the digital revolution, or the influence that a few multinational corporations exert on our lives.

These challenges may highlight how weak Europe is on the world stage. But what is the alternative? Do those who advocate for a return to national borders believe that they can better respond to the borderless challenges of a digital age or a changing climate? The anger they irresponsibly fuel cannot lead to useful, positive responses to these issues.

Europe is in peril, because it has not defended its ideals or taken up a global leadership role. Democracy, deliberation and consensus appear too meek, next to the simple answers peddled by so-called “illiberal” leaders.

Those who analyze the irresistible rise of reactionary movements in Europe often point the finger at the Kremlin. They are right. The facts are clear and documented for those who want to see them.

Europe has guaranteed the rights, freedoms and prosperity of 500 million citizens for a period longer than any other in our history.

Europe, its institutional existence and its values are under attack. The freedoms we enjoy are threatened at the EU’s borders — sometimes at the cost of many lives, as in the case of Ukraine, where the illegal Crimean annexation and the war in the Donbas have caused so much damage. Within the EU, this attack takes the shape of dangerous disinformation campaigns.

But the responsibility also lies with us. We must fight back — not just against “enemies” but for Europe, for our ideals and our future. We must remember why the hard-won freedoms we enjoy are worth fighting for.

Europe is more than just a currency, a set of institutions or a collection of treaties.

Europe has guaranteed the rights, freedoms and prosperity of 500 million citizens for a period longer than any other in our history.

But this hard-won democracy and safety, our ability to vote out our leaders, to take part in civic life, can be undone. We cannot afford to sit idly by while a reactionary revolution attempts to dismantle our free, pluralistic societies. We must stand up and resist what Václav Havel called “the aggression of the darkest moments of our past against an honorable future.” We must find the collective stamina to sustain our democracies, and convince Europeans they are worth fighting for.

Next year’s European election is a chance to debate our shared future. We have to seize on this opportunity — we don’t yet know how many more we have left.

Franziska Brantner is a Green member of the German parliament.

Alexis Prokopiev is founder of Russie-Libertés, a Paris-based NGO focused on democracy in Russia.

Anna Garmash is founder and chair of Ukraine Action, a Ukrainian diaspora NGO.

Evan O'Connell is a Paris-based pro-EU activist and political commentator.

Małgorzata Szuleka is an advocacy officer at the Helsinki Foundation for Human Rights in Poland.

Blaise Gonda is a Franco-Hungarian pro-EU activist and academic.