Risk-free government bonds and the tax burden: How to resolve the dilemma?

The conventional theory tells us that government bonds are risk-free because governments can increase taxes at any time to restore fiscal solvency. But today, given the high level of the tax burden, the fear of the effect on demand and tax competition between countries, governments are no longer free to increase taxes. For government bonds to be risk-free, savers must therefore think that the central bank can intervene with quantitative easing and buy government bonds at any time. If, in the future, when quantitative easing has been suspended, then central banks will have to send the message that it may be resumed at any time. This will be the price to pay to preserve the risk-free nature of government bonds.