Slights and barbs have marred relations between France's Emmanuel Macron and Turkey's Recep Tayyip Erdogan for years, but the row over cartoons of the Prophet Muhammad has dragged them to a new low which could have more lasting consequences.
Officials on both sides describe a series of behind-the-scenes frosty exchanges and grudges between the two leaders going back years, long before the row of the past few weeks.
But if they cannot find a way to mend bridges, momentum is likely to build for a proposal, driven by France, for European Union sanctions on Turkey's already-fragile economy, according to Turkish analyst Sinan Ulgen.
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