The two NATO allies are working to establish what Turkey says will be a “safe zone” along the border in northeast Syria Akar said Turkish and US soldiers had flown three helicopter reconnaissance missions over the area in recent days ANKARA: Turkish Defence Minister Hulusi Akar said Friday that joint patrols with the United States would begin on Sunday in northeastern Syria in the area marked out to become a "safe zone". "We are planning to start joint patrols on September 8," he told reporters. An agreement reached on August 7 between Ankara and Washington aims to establish the safe zone between the Turkish border and the Syrian areas east of the Euphrates river controlled by the Kurdish YPG militia, which is an ally of the US but seen as a terrorist organisation by Turkey. Akar said Turkish and US soldiers had flown three helicopter reconnaissance missions over the area in recent days. President Recep Tayyip Erdogan this week repeated his threat to launch an operation against the YPG in Syria unless progress was made on setting up the safe zone. Turkey has repeatedly warned against any delay in the project. No details on the timeframe and size for the zone have been made public, although Erdogan said his US counterpart Donald Trump had promised it would be 32 kilometres (20 miles) wide. A joint centre of operations was recently established as part of the agreement. It has twice launched cross-border operations into Syria against the YPG and Daesh, in 2016 and 2018.