TABQA, Syria (Reuters) - Arab and Kurdish militias expect to storm Islamic State’s Syrian stronghold of Raqqa in early summer, one of their commanders said on Friday, with the help of weapons they are awaiting from the U.S.-led coalition against IS.

Syrian Democratic Forces (SDF) fighters stand in the town of Tabqa, after capturing it from Islamic State militants this week, Syria May 12, 2017. REUTERS/Rodi Said

Abdul Qader Hevdeli, a commander of the militias known as the Syrian Democratic Forces (SDF), said they were expecting supplies including armoured vehicles as they embark on what will be one of the defining battles of the war against the militants in Iraq and Syria.

While the coalition has already armed Arab fighters in the SDF, the White House this week authorized supplying weapons for the first time to its most powerful element, the Kurdish YPG, to help in the Raqqa assault.

That has infuriated Turkey, which sees the YPG as an extension of the Kurdistan Workers’ Party (PKK) that has fought a three-decade insurgency for Kurdish autonomy and rights inside Turkey.

Asked about the timing of an assault on Islamic State’s de facto capital in Syria, Hevdeli told a news conference: “I can’t specify exactly, I believe entering and storming the city will happen at the start of the summer.

“At the start of entering, of course, as (the coalition) promised us, there will be support in the form of specialised weapons, armoured vehicles or others.”

He said that weapons approved by the White House for the YPG had yet to arrive, but added: “I believe these weapons or this support will arrive soon.”

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The SDF, an alliance of militias including Arab groups and the Kurdish YPG militia, has been waging a campaign to isolate and ultimately capture Raqqa since November, with backing from the U.S.-led coalition.

A coalition spokesman said on Wednesday the United States may start distributing some arms and equipment to Kurdish YPG fighters in Syria “very quickly” but it will be done incrementally and closely monitored.

TABQA MILESTONE

Hevdeli was speaking to reporters in Tabqa, which along with its nearby dam on the Euphrates River was captured by the SDF this week - a major milestone in its campaign against IS.

The SDF said in a statement that Tabqa would be turned over to a civilian council once fully secured. The authority that oversees the hydroelectric Tabqa dam would remain “a national Syrian institution that will serve all the regions of Syria without exception”.

The SDF have also captured a major airbase near Tabqa, some 50 km (30 miles) west of Raqqa, in the latest phase of their operation against IS. Sandbag fortifications left behind by Islamic State fighters lined the roadside in Tabqa city.

Some 25,000 people had been displaced from Tabqa during fighting in recent weeks, staying in informal settlements south of the city, a U.N. refugee agency official in Syria, Roupen Alexandrian, said. Displaced residents had begun to return after Tabqa was captured, he added.

“And now with the advancement of SDF toward Raqqa, huge short-distance displacement is also taking place and also some displacement toward Tel Samen, north of Raqqa,” he said.

The SDF called on the people of the area to “organise themselves so they can protect the city and the area themselves”.

“The civilians that are present in the city, or the ones who were scattered in the conditions of war, ... will return to their homes and will live with honour and dignity,” Hevdeli said.