Is there a public debt sustainability problem in the euro zone?

The European Union's fiscal rules will be applied again from 2024 (fiscal deficit below 3%, reduction in the public debt ratio, with an adjustment period that depends on the implementation of structural reforms). But is the implementation of these restrictive rules (the public debt ratio must be reduced by at least 1 percentage point per year for countries where it exceeds 90% of GDP) justified by the fact that public debt sustainability is not ensured at present? The public debt is not sustainable if the primary fiscal surplus is lower than the product of the public debt ratio and the gap between real long-term interest rates and real long-term growth. In addition, we must bear in mind that part of the public debt is held by the ECB, and that the interest paid on this part of the public debt is re paid by the ECB to governments. All in all, the calculation shows that neither the euro zone nor the largest euro-zone countries are currently ensuring their fiscal solvency. The countries that are furthest from achieving fiscal solvency in 2023 are France and Italy.