Iran’s supreme leader Ayatollah Ali Khamenei on Tuesday told visiting Turkish President Recep Tayyip Erdogan that any offensive by Ankara in northern Syria would be “detrimental” to the region. His statement came shortly before Iran’s ultra-conservative President Ebrahim Raisi hosts his Russian and Turkish counterparts for talks on the Syrian conflict. Erdogan has repeatedly threatened to launch a military offensive in northern Syria to create a “safe zone” that would drive Kurdish militants 30 kilometres (19 miles) back from the Turkish border. Mapping the complexities of Turkey’s new Syria o…