By Thomas Escritt and Andreas Rinke

BERLIN (Reuters) -A photograph of Zikim Beach in southwestern Israel near Gaza, attacked by Hamas militants in boats in both the 2014 and current Gaza wars, hangs on the wall of new German Chancellor Friedrich Merz's office.

The idyllic shot of a row of beach huts restored after the Hamas raids attests to the arch-conservative being a passionate supporter of Israel, in keeping with Germany's long-time solidarity in atonement for the Nazi-era Holocaust.

So Merz's rebuke of Israel on Tuesday over its widening military operations in Gaza was a remarkable turnabout for many.

"What the Israeli army is doing in the Gaza Strip, I no longer understand the goal," he said. "To harm the civilian population in such a way, as has increasingly been the case in recent days, can no longer be justified as a fight against terrorism."

Foreign Minister Johann Wadephul then said there could be unspecified "consequences" in a sequence of conservative remarks coordinated with Social Democrat coalition partners, marking a rhetorical break from decades of unconditional German backing for a country to which Berlin feels committed by history.

Separately, Merz's fellow German conservative, European Commission President Ursula von der Leyen, said deaths of children in the Gaza war have been "abhorrent", reflecting the breadth of disquiet in German elite circles.

Alongside membership of NATO and the European Union, backing for Israel was the third pillar of Germany's quest for international rehabilitation after the Holocaust against Europe's Jews in World War Two.

While some antisemitism lingered - Konrad Adenauer, post-war Germany's first chancellor, justified restitution payments for Israel that laid the foundation of German-Israeli relations by the need to appease "the power of the Jews" - the commitment to Israel's security shaped generations of German politicians.

But the intensity of Israel's war in Gaza, which has killed over 53,000 Palestinians and was triggered by Hamas' October 7, 2023 cross-border attack that killed around 1,200 people, has contributed to a pronounced shift in German public opinion.

Only 36% of Germans now have a positive view of Israel, a 10 percentage point fall from four years ago, a survey for the Bertelsmann Foundation found.

Germans under 40 consider themselves less informed about Israel than the over-60s, and are also less likely to believe relations should be shaped by memory of the Holocaust.

This shift has imposed a dilemma on Merz, who on winning February's national election had promised Benjamin Netanyahu he would help the Israeli prime minister defy an International Criminal Court arrest warrant if he visited Germany.

"They understand they have two opposing obligations and have to choose between them," said Moshe Zimmermann, an eminent historian of Germany at Israel's Hebrew University. "In the past they would have said our obligation to Israel is primary. Now they have to weigh the alternatives differently."

'TIMES CHANGE'

Germany and other European countries condemn Russia for violating international law with its invasion of Ukraine and have imposed unprecedented punitive sanctions on Moscow, seeking backing for isolating it from countries as diverse as South Africa, Brazil and Saudi Arabia.

Western powers have not taken the same approach to Israel amidst steady accusations by rights and humanitarian groups of international law violations in its conduct of the war in Gaza, with many Palestinian civilian deaths, widespread devastation of infrastructure and a rising famine risk under Israeli blockade.

"Times change," said Zimmermann.

The trigger for German leaders' rhetorical shift came when a May 25 deadline passed without Israel heeding a European call to completely lift a blockade of humanitarian aid into Gaza.

Wadephul said there could be now no "obligatory solidarity" with Israel, while Finance Minister Lars Klingbeil, the Social Democratic leader, said human rights standards were being violated in the Gaza Strip.

The shift brings Germany into line with major European partners that have also been loath to pointedly criticise Israel over Gaza. France and Britain, joined by Canada, aired a similar message last week. Italy echoed it on Wednesday.

In response, Netanyahu has accused British, French and Canadian leaders of being "on the wrong side of history".

At a conference on antisemitism in Jerusalem on Wednesday, Foreign Minister Gideon Saar said Israel was "the most attacked and threatened country in the world", adding: "The attempt to deny Israel its right to defend itself is horrific."

Israel has denied violating international law in Gaza, saying it is targeting only Hamas militants and accusing them of using civilian buildings for operational cover. Hamas denies this.

CULTURAL CHANGES IN GERMANY

The change in Germany's tone also reflects a country that is far more ethnically and culturally diverse than in decades past.

Fully a quarter of Germany's 80 million people now have a migration background - meaning at least one parent is an immigrant - and many of them are of Middle Eastern or Muslim heritage with an affinity for the Palestinians.

"If you're asking a German-Syrian to come to terms with Germany's responsibility for the Holocaust, that's really strange," said Omer Bartov, a Holocaust historian at Brown University in the U.S.

The consequences for German policy are unclear, Bartov said.

Germany continues to sell weaponry to Israel, remains its largest European trade partner as well as on Israel's side in South Africa's genocide case against Israel in the International Criminal Court in The Hague.

"It's a rhetorical shift and it could be very significant," Bartov said. "But the Israeli navy is made in Germany and right now the Israeli navy is firing shells into Gaza.

"As long as they (Germany) don't take some (concrete) step, Netanyahu has no reason to worry right now."

(Reporting by Thomas Escritt, Andreas Rinke and Sarah Marsh in Berlin, James Mackenzie in Jerusalem; writing by Thomas Escritt; editing by Mark Heinrich)