The landslide “no” vote in yesterday’s referendum on austerity in Greece is an overwhelming popular repudiation of the European Union and the austerity agenda it has pursued across Europe since the 2008 economic crisis.

The vote is an extraordinary act of political courage, defying threats and intimidation from the European Union, the US government and the Greek ruling class. Together with last Friday’s massive anti-EU austerity demonstration in Athens, the overwhelming “no” vote on Sunday has once again revealed the social force that can put an end to austerity and political reaction—the working class.

Berlin led the campaign for a “yes” vote in support of the EU’s last set of austerity demands. German government officials made it clear that their intention was to use such a vote to push for the ouster of Greece’s Syriza-led government.

In advance of the referendum, Berlin warned that the EU would respond to a “no” vote by cutting off credit to Greece’s financial system and bankrupting the country. This would be followed by the expulsion of Greece from the euro zone.

The Greek media campaigned relentlessly for a “yes” vote. Retired Greek army officers intervened publicly on the eve of the referendum to attack Prime Minister Alexis Tsipras and demand that the Greek people back the EU’s austerity demands. This was a blatant act of political intimidation, which, in a country still traumatized by the seven-year dictatorship of the Greek colonels, carried an implied threat of military coup.

Fully 61.3 percent of the Greek people, drawn largely from the working class and poorer layers of the population, responded by voting “no.” This landslide, coming after media polls had predicted a close vote, stunned the political establishment in Greece, Europe and the United States.

The “no” camp won decisively in all 13 of Greece’s administrative regions, according to Interior Ministry figures. Greek youth, over half of whom are unemployed due to the collapse of the economy under the impact of EU policies, voted “no” by fully two to one.

The “no” vote exposed the fact that the policies of the EU under the leadership of German Chancellor Angela Merkel have no popular support or democratic legitimacy.

Since 2009, the major powers have sought to rescue European capitalism from the impact of the global economic crisis by effectively seizing hundreds of billions of euros from the European population—€65 billion in Greece alone, or over €17,000 for each of Greece’s 3.7 million households.

With Sunday’s vote, articulating the opposition to EU austerity of the working class throughout Europe, the Greek masses are demanding not minor modifications to the austerity agenda, but its overturn.

Disavowed not once but twice by the Greek people—once in January when Syriza was elected based on its pledges to end EU austerity, and again in yesterday’s referendum—the European Union stands exposed as a ruthless instrument of finance capital, working in league with Greece’s ruling elite to ride roughshod over the sentiments of the Greek people and impose a policy of economic devastation.

The “no” vote has further exposed the cowardice and bankruptcy of Syriza. Prime Minister Tsipras went on national television Sunday night to stress that Greek negotiators would return to austerity talks with the EU, insisting that “the mandate you give me is not one of rupture with Europe.”

No one was more terrified than Tsipras by the outpouring of popular opposition to EU austerity, seen first in Friday’s “no” demonstration in Athens and then in Sunday’s vote. Since coming to power last January, he and his government have sought to contain and dissipate social opposition to the European Union and tie the working class to austerity and capitalism.

The actions of the Syriza-led government during the referendum campaign were cowardly and two-faced. Top government officials, including Tsipras and Finance Minister Yanis Varoufakis, indicated that they would resign in response to a “yes” vote and help their successors impose EU austerity measures. As for their response to a “no” vote, Tsipras said last Wednesday that he would seek to negotiate a settlement with the EU based on a Greek offer that accepted virtually all the social cuts demanded by Brussels.

Syriza’s referendum maneuver, a barely disguised attempt to engineer a vote of no-confidence in its own government, exploded in its face. Tsipras and company were as stunned by the “no” vote as Merkel. Their negotiators headed as fast as they could for Brussels. Varoufakis and Syriza spokesman Gabriel Sakellaridis predicted that a deal for a new financial aid package in exchange for further austerity measures could be reached in 24 to 48 hours.

In the aftermath of the referendum, the question facing the Greek working class is: what next? How is the fight against austerity to be carried forward? There should be no illusions that Syriza or the EU will modify their policies in response to the “no” vote.

Whatever divisions may emerge within the EU on how to respond to the setback it has suffered in the referendum—with some factions calling for crushing Greece and expelling it from the euro zone, others for working with Syriza to negotiate a deal—they will not change the class policy of ruthless austerity against the workers. EU Parliament head Martin Schulz indicated this weekend that the euro will no longer be available as a method of payment for Greece and that Greece should introduce a separate “parallel currency.”

It is critically important to draw the political lessons of this experience. There is enormous opposition in the working class in Greece and internationally to austerity. However, this opposition can be mobilized only if the working class breaks with Syriza and mounts a revolutionary struggle against the EU and the imperialist powers as well as their base of support within Greece itself—the Greek capitalist class.

As he addressed a crowd of hundreds of thousands in Athens last Friday, a shaken Tsipras insisted that the mass demonstration was not a “protest.” He declared, “Regardless of Sunday’s decision, on Monday the Greek people will have absolutely nothing dividing them.”

This is a patent lie. The “no” vote itself has made clear the social chasm separating the working class from the ruling elites of Greece, Europe and America. The referendum result has brought to the fore the enormous class tensions within Europe and above all within Greece itself.

As Syriza repudiates the popular will and seeks to continue its talks with the EU, it will base itself ever more directly on the security forces to deal with internal opposition. Syriza Interior Minister Nikos Voutsis is overseeing planning, code-named Operation Nemesis, for the mass deployment of riot police and army units to crush social unrest.

Such preparations are the clearest warning that the fight against austerity in Greece is a fight against an entire social order. It requires a determined struggle to mobilize the international working class on a revolutionary, socialist perspective against both the imperialist powers and the local agents within Greece of international finance capital—the Greek bourgeoisie and all of its political representatives.