Some of the 40 migrants who were aboard the Sea-Watch 3 rescue ship disembark at the port of Lampedusa, Italy, on June 29. (Elio Desiderio/EPA-EFE)

Andrea Mammone is a visiting research fellow in the Robert Schuman Centre for Advanced Studies at the European University Institute and a historian of Europe at Royal Holloway, University of London.

After waiting for two days for permission to dock in Lampedusa, Italy, Sea-Watch 3 — a humanitarian boat carrying 40 Libyan migrants rescued from a flimsy dinghy in the Mediterranean — finally defied Italy’s orders and entered the port on Saturday. As soon as the vessel docked, the ship’s German captain, Carola Rackete, was arrested and, according to her lawyer, accused of “resisting a war ship” — a charge that carries up to 10 years in prison.

Sea-Watch immediately tweeted a statement from its chairman, Johannes Bayer, which read: “We are proud of our captain, she did exactly the right thing. She upheld the law of the sea and brought people to safety.” Italy’s deputy prime minister and interior minister, the far-right and anti-immigrant Matteo Salvini, responded by calling the vessel’s action an “act of war.” His outrageous statement reflects a growing struggle within Europe over how governments should respond to the influx of migrants undertaking dangerous journeys across the Mediterranean — and also serves a unique political purpose.

This is not the first time that the fate of a migrant rescue vessel became a symbol for a divided Europe. A year ago, the newly established Italian government launched its anti-immigrant enterprise by not allowing another rescue boat, the Aquarius, to head toward Italian land. It is then that Salvini embarked on his “let’s shut the ports” policy. Aquarius’s asylum seekers were hosted by Spain, while last week, five other European countries agreed to take in Sea-Watch’s migrants.

But the situation is far from resolved. The case has caused tension between Italy and other European Union member states, including France and Luxembourg, as well as the United Nations and E.U. institutions. Officials from Germany and the Vatican have said that Salvini’s hard-line migration policy essentially criminalizes those saving lives in the Mediterranean.

Meanwhile, another migrant rescue charity has said it is ready to force Italian authorities’ orders and face prison time to save the lives of people escaping conflict, poverty and inhuman conditions in Libya’s detention centers. On Monday, the other Italian deputy prime minister, Luigi Di Maio from the populist Five Star Movement, responded by writing that Italy should seize all humanitarian vessels defying laws. All this could soon bring Italy’s anti-immigrant policies to a head.

Preventing migrants from docking on European coasts or crossing borders has a specific significance. It has become a way for right-wing politicians to challenge the power of international courts, the humanitarian narratives promoted by the Vatican and Pope Francis, the most cosmopolitan features of international organizations and the multicultural values embodied in the progressive and educated liberal elites. This aligns with nationalist calls for the preservation of culturally, ethnically and ideologically homogeneous communities, and is a way to reject a type of modernity. But at the same time, it also distracts citizens from real problems.

In Italy, these issues are grave. It is the third-largest economy in the euro zone but has suffered from recession after recession in the past decade. Unemployment is still an enormous problem, and youth unemployment in particular stands at more than 30 percent. The country has also racked up an incredibly high public debt. The European Commission might soon start take legal action against Italy for its excessive deficit and not respecting spending rules.

Yet politicians found another group to blame for these troubles. “In the last few years, European bureaucrats have damaged the Italian economy,” Salvini declared. He has also repeatedly blamed migrants for Italy’s ills in the past.

Such scapegoating is not a novelty in the history of the far right. The Jewish community was a first target before World War II. Following the mass migrations that came after decolonization, far-right leaders identified a new enemy: the immigrant. In 1968, the conservative Enoch Powell, gave an infamous speech in which he criticized integration and said, “We must be mad, literally mad, as a nation, to be permitting the annual inflow” of migrants. In the 1970s, the National Front, led by former leader Jean-Marie Le Pen, popularized a line that translates to “1 million [French] people unemployed, there are 1 million immigrants too many. France and French citizens come first.”

Today, this rhetoric is popular across Europe — and beyond. Le Pen’s anti-immigrant slogan has found a contemporary equivalent in President Trump’s “America First” policies and Salvini’s “Italy First” propaganda. The horrifying anti-immigrant message of Powell’s speech partly influenced recent Brexit propaganda. And Salvini is just one of many European nationalist politicians, including Hungary’s Viktor Orban and Austria’s Heinz-Christian Strache, that have demonized immigrants for their own political gain.

Salvini’s scapegoating of migrants saved from the sea is part of this struggle for the shape of wealthy, industrialized nations — a social and political struggle that will define future societies as open or closed, and embracing solidarity or dehumanization. Italians should not let him get away with it.

Read more:

Sebastian Mallaby: Italy’s new government could be the force that finally breaks Europe

Fareed Zakaria: The West’s crises are over, but the populist fury remains

Andrea Kendall-Taylor and Alina Polyakova: Populism and the coming era of political paralysis in Europe

The Post’s View: Will Europe do anything to stop the drownings of migrants?

Anne Applebaum: How Libya continues to flummox Europe