Most of the tens of thousands of migrants who swam into the Spanish exclave of Ceuta on Thursday have now returned to Morocco, escorted to the border by Spanish soldiers and police.

But the extraordinary surge of arrivals has left at least 72 people dead, their bodies pulled from the sea where they floated alongside abandoned rubber rings and flippers.

This week’s events have also shaken Europe politically, once again exposing divisions over the sensitive issue of migration.

And they’ve left lingering questions about what sparked the sudden influx: whether social media posts promising an easy path to Europe just went viral or this was something more deliberate, even organised.

Whatever the cause, Spain’s socialist prime minister is angry with the response.

Pedro Sanchez has hit out at some in the EU for “attacking” Spain in this crisis, playing politics instead of showing support.

He meant Italy, above all.

Fratelli d’Italia, the hard-right party of Prime Minister Giorgia Meloni, had been quick to post images of migrants racing through the streets of Ceuta.

“This is the Sanchez model the Italian left wing likes so much,” the caption crowed.

Meloni then announced she was suspending Italy’s Schengen agreement with Spain that allows for the free movement of people, citing a security threat.

Madrid is fuming.

The way Spain sees it, the crisis has been contained and Ceuta is not in the Schengen zone so Moroccan migrants were never going to head for mainland Europe, unchecked.

Meloni knows that.

But she faces elections next year with her coalition losing ground to a new and virulently anti-immigrant party. This was a chance to sound tough herself and claw back votes and she leaped on it.

Italy is not the only country to see Spain as soft on migration, though.

Meloni’s call for an urgent meeting of interior ministers to be held on Tuesday was signed by almost two dozen EU heads of state, calling for the elimination of all policies that could be “pull factors” to Europe.

Above all, they mean Spain’s controversial move to allow hundreds of thousands of undocumented migrants apply for residence and work permits and “regularise” their status.

The government’s pragmatic: Spain is ageing and needs workers.

But those who flocked to the beaches of Ceuta this week were not heading to sign up for a campaign that’s already closed.

Sanchez himself points instead to a recent ruling by Spain’s Supreme Court: it said those who enter by sea cannot be pushed back immediately.

The prime minister argues that was misrepresented by smugglers to promise an easy path to Europe.

The crowd heading for Ceuta didn’t need to pay smugglers, though, because most were Moroccan and the route is well known.

The message was actually spread online.

Migrants have shown social media posts to reporters with people shouting that “Spain is Open” and jumping into the sea.

Multiple accounts we’ve checked ourselves show young people in wetsuits and flippers, or filming themselves already swimming, mixed with pictures from inside Ceuta itself.

Some have only been active for weeks. Several have tens of thousands of likes.

All their promises were false.

The crowds who made it to kiss the shore in Ceuta with joy were met with nothing. Without food or shelter, and with no way on to continental Europe, most quickly turned back.

So have migrants been “weaponised” as happened a few years back in Belarus, for example?

If so, who did it?

For now we only see those enjoying the results.

The global right wing are “hyperventilating with happiness”, as journalist Andrea Rizzi wrote in Spain’s El Pais newspaper.

US President Donald Trump, angry at Spain for opposing his war on Iran, has talked of a “catastrophe” and an “invasion”. Like Meloni, he has an election looming.

Russia has been gloating, too: it loves chaos and division in Europe. Anything to weaken Ukraine’s allies.

As for Morocco, it’s blaming “criminal organisations”. But its border guards must have seen the crowds building.

The last time something similar happened, albeit smaller, Spain and Morocco were at loggerheads over Western Sahara, a former colony.

There are new tensions, right now.

Sanchez is emphatically not blaming Morocco for what happened, calling Rabat a “good ally”.

But his critics call that appeasement and say he should be “showing teeth”.

For now, Spain is busy protecting Ceuta against further incident.

It is extending the border fence out to sea, attaching long lines of orange buoys to the jetty which ships will then patrol to deter future swimmers.

Next week, EU interior ministers will talk about strengthening external borders, with those on the populist right emboldened.

Travellers from Spain to Italy face random document checks by police for a few weeks.

So no huge change.

Except for the dozens of young people who set out to sea, chasing a vision they’d seen online, and are now being sent back to Morocco in coffins.