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The killing of Hamas's political leader Ismail Haniyeh in a suspected Israeli strike in Tehran early on Wednesday has drawn thousands of Turks on to the streets of Istanbul, waving Hamas and Palestinian flags.

A merchant sold satin scarfs printed with the words, “martyr Ismail Haniyeh”. Others carried banners showing the faces of other Hamas leaders, including its founder Ahmed Yassin, who was killed by Israel in 2004.

“We came here today because a great mujahid, Ismail Haniyeh, was lost, and we are mourning,” Ramazan Citak told The National at the march’s starting point at Fatih Mosque in Istanbul on Wednesday night.

Turks across the political spectrum support Palestinian rights, and Turkey’s official position backs a two-state solution. The issue is particularly emotive for President Recep Tayyip Erdogan's generally more conservative and pious support base.

“The Palestinian resistance and Jerusalem are Turkey's red line. Hamas is the one carrying the flag for the independence of the occupied lands,” an adviser to the Turkish President told The National.

Condolences poured out from Turkish government officials following Mr Haniyeh’s death.

“We condemn the murder of Hamas political bureau chief Ismail Haniyeh, one of the leading figures of the Palestinian cause, as a result of a Zionist assassination in Tehran,” said Omer Celik, spokesman for Mr Erdogan’s ruling Justice and Development Party (AKP).

Israel has struck Hamas leaders in Iran, Lebanon and Palestine, but not in Turkey so far. Ankara warned Israel against doing so following the assassination of Hamas official Saleh Al Arouri in Beirut in January.

Mr Erdogan has ruled Turkey for 21 years and in that time has built a reputation as a staunch supporter of the Palestinian cause and Hamas.

Ismail Haniyeh went on an extended visit to Turkey in April. President Erdogan welcomed him in his Istanbul office, where the pair exchanged friendly embraces.

Other Turkish political parties in parliament also met with the Hamas leader, and described him as “our dear brother”.

Some of the movement's senior officials have also spent long periods in Turkey, and Israel has accused Ankara of offering Turkish passports to some of its members. Turkey never confirmed the allegations.

At the same time, Turkey has had a roller coaster of diplomatic relations with Israel. Following the killing of 10 Turkish citizens on an aid flotilla attempting to enter Gaza in 2010, Turkey expelled the Israeli ambassador and officially downgraded diplomatic ties. Relations warmed before ambassadors were told to leave again in 2018, returning in 2022.

Over the same period, trade ties built up between the two nations, with Turkish companies exporting significant quantities of cement, steel and other building materials to Israel.

Mr Erdogan has also distanced himself from western countries over the war in Gaza, accusing them of complicity in the deaths of Palestinians.

That is part of a broader political attempt by Mr Erdogan and other senior officials to portray Turkey as an alternative centre of power and protector of Muslims. They warn that support for Israel will create long-term mistrust and resentment among Middle Eastern countries.

“The globalist neoliberal elites that rule the US and the powers behind them are trying to create war and chaos in order to survive,” the presidential adviser said.

“Spreading the conflict and assassinations are increasing hatred towards the US, Israel and England. If they cannot develop another method, they will not only lose but will also pay a very heavy price.”

After Hamas’s October 7 attacks, Turkey initially took a conciliatory position as it attempted to play a mediating role between Hamas and Israel. But its efforts were overshadowed by the US, Egypt and Qatar, and Mr Erdogan’s rising criticism of Israel also appeared to be a response to domestic anger over ties with the country.

In early May, Turkey banned imports from and exports to Israel, prompting a drop off in trade previously worth hundreds of millions of dollars a month. In its latest foreign trade figures for June, Turkey's Statistical Institute has no numbers recorded for Israel.

Mr Erdogan’s increasingly harsh comments about Israel could harm any prospects of a bigger Turkish role in the Palestinians’ future, some observers say. The Turkish leader has repeatedly compared Israeli Prime Minister Benjamin Netanyahu to Adolf Hitler; Israeli officials have responded with criticisms of Turkish support for Hamas.

“Turkey’s one-sided stance means it has very little influence in the diplomatic sphere on discussions about the future of Gaza,” Gallia Lindenstrauss, a researcher at the Tel Aviv-based Institute for National Security Studies, told The National.

Even before Mr Haniyeh’s killing this week, tensions had escalated between Turkey and Israel after Mr Erdogan threatened to intervene in the country. It prompted Israel to call on Nato countries to expel Turkey from the group. Israel is not a member of the alliance but has been an official partner since 1994.

“Partners do not have the authority to ask the alliance to 'expel a member' from Nato,” Mehmet Ceylan, a former Turkish ambassador to Nato, told The National. “There is no legal provision or a procedure to kick out an ally from the alliance.”

However, not all Turks are as supportive of Hamas as Mr Erdogan and his conservative allies.

Following Mr Haniyeh’s assassination, a senior official from Turkey’s main opposition, the Republic People’s Party (CHP), condemned the attack but did not glorify the Hamas leader, framing remarks around concerns over regional escalation and the need to maintain a focus on Gaza.

“We are especially concerned that this will not contribute to the peace of the region, that it will escalate the tension and the conflict,” CHP deputy chairman Murat Emir told Turkish legislators in Ankara. “Our desire is for the whole world to pay attention to the massacre, especially in Gaza, and to do whatever it can to stop it.”

About three-quarters of Israel-Turkey trade was Turkish exports, meaning that firms have lost a key source of income at a time when its economy is suffering a years-long crisis and inflation of over 70 per cent.

Many Turks take issue with the Israeli state, rather than its people.

“In Israel, there are lots of people who want peace,” said Ince Erkul, an engineer who attended the Istanbul march. “It’s just Netanyahu and some Zionist groups who want war.”