Turkey’s president has warned the US it has made a “grave mistake” asking for protection for Kurdish fighters battling Islamic State in Syria and threatened once again to launch an assault against them. Recep Tayyip Erdogan, who considers the Kurdish People’s Protection Units (YPG) terrorists, said Turkey would “not make concessions” and said preparations for an offensive were nearly complete. “John Bolton has made a grave mistake on this issue,” a furious Mr Erdogan told parliament as the US national security adviser arrived in Ankara for talks with Turkish officials. “The (YPG’s) fight with Islamic State in Syria is a huge lie.” Mr Bolton was in Turkey on Tuesday as part of a tour of the Middle East with Mike Pompeo, US Secretary of State, aimed at limiting damage over the announcement by Donald Trump, the US president, that he would remove its troops from Syria. Such a move would leave YPG allies, whose fighters have led a coalition to defeat Isil, exposed to a Turkish attack. YPG fighter holds a sniper rifle on his shoulder as he attends the funeral of a slain commander in the northeastern city of Qamishli Credit: AFP Mr Bolton said on Sunday he would be seeking assurances from Ankara that they would not attack the YPG as a condition to a US withdraw, which Mr Trump had failed to address during a December phone call with Mr Erdogan, in a bid to salvage relations with the Kurds. Mr Bolton met for roughly two hours with Ibrahim Kalin, his Turkish counterpart, and other senior officials at Ankara’s presidency complex but was snubbed by Mr Erdogan himself, reflecting just how at odds the Nato partners are on the issue. Mr Trump, in a tweet before Christmas, declared Isil had been defeated and said the US’s 2,000 or so troops would be returning as soon as possible. However, Mr Bolton, Mr Pompeo and even Mr Trump have tried to backtrack the comments, offering differing timelines ranging from 30 days to four months for the withdrawal. The shifting timetable has left allies and other players in the region confused and jockeying for influence over a withdrawal strategy that appeared to be a work in progress. In Turkey’s case, it appears to have emboldened Mr Erdogan, who was reported to have asked the US to hand over its 22 military bases in Syria or dismantle them. Responding to Mr Erdogan’s threats, a top Syrian Kurdish official said his fighters are prepared to confront Turkish forces if they enter northeastern Syria. Shahoz Hasan, co-chair of the largest Kurdish group in Syria the Democratic Union Party, or PYD, says it was clear from the latest statements that Turkey has planning an assault. “We will be ready.” he said. Any such offensive would likely see the YPG redirecting fighters battling the last Isil to the northern border with Turkey. Despite Mr Trump’s claim, fierce fighting is still ongoing for a small pocket of territory in eastern Deir Ezzor province. In a stark reminder of the lingering threat, a war monitor reported that the jihadists had killed 23 US-backed Syrian Democratic Forces (SDF) fighters in a counterattack in eastern Syria on Monday aimed at defending their last bastion. Isil took advantage of poor visibility to unleash suicide attackers on SDF along the front line in the Euphrates valley, the UK-based Syrian Observatory for Human Rights said Tuesday.