The United States is to send another 200 troops to Syria to support moves against Daesh's de facto capital of al-Raqqa, Defence Secretary Ash Carter said Saturday, bringing the total number of US troops in the war-torn country to 500.
In a speech at a security conference in Bahrain, Carter said the troops, who included advisors and bomb disposal experts, would help train local Kurdish and Arab forces to retake the Daesh stronghold.
Carter implied that the US administration is planning to rely on the Kurdish-led Syrian Democratic Forces (SDF) and local allies to capture the city, despite objections from neighboring Turkey.
The SDF, which in early November launched a US-backed campaign against al-Raqqa, Saturday announced that operations were moving into a new phase focussed on the city's western front.
Turkish President Recep Tayyip Erdogan said in November that his forces would be the ones to move on al-Raqqa, while Carter had said that Washington was talking to Ankara about "a possible role for Turkey in that further down the road."
In Bahrain on Saturday, Carter said: "We're now helping tens of thousands of local Syrian forces to isolate Raqqa, from which they're now only 15 miles (24 kilometres) away."
"And as the isolation phase continues according to plan, we're helping them generate the additional local forces necessary to seize and hold that city."
The US alliance with the SDF has alarmed Turkey, which distrusts the alliance's dominant Kurdish element due to their links with banned Kurdish rebels operating on its own soil.
The US and the SDF have emphasized the role being played by Arab forces within the alliance. In addition to Turkish sensitivities, al-Raqqa is itself a mainly ethnically Arab city.
In recent days, Turkish pro-government media has expressed alarm about potential US moves to arm Kurdish forces in Syria.
Turkey is backing Syrian rebel forces who are fighting Islamic State for control of the town of al-Bab, further west. The Turkish-backed rebels have also repeatedly clashed with the Kurdish-led forces.
Later on Saturday, the SDF announced what it described as the second phase of its campaign against al-Raqqa.
The new phase will focus on isolating the city's western approaches after the Kurdish-led forces' previous advances on the northern front, spokeswoman for the alliance's al-Raqqa operations Jihan Sheikh Ahmed said.
Ahmed said that 1,500 Arab locals from the region had joined the operation recently after undergoing training by the US-led coalition against Daesh.
She also confirmed an announcement by US military spokesman John Dorrian that Arab forces linked to former Syrian opposition leader Ahmed al-Jarba would be joining the operation against al-Raqqa.
The announcement comes as fighting in the city of Aleppo, 200 kilometres to the east, intensifies, with the Syrian army seizing most of the rebel-held enclave in recent weeks and forcing tens of thousands of residents to flee.
US Secretary of State John Kerry discussed the Syria crisis with his counterparts from Britain, Germany, France and Turkey at a meeting in France later on Saturday.
By Helen Livingstone
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