What is behind Merz's plans to cut social security while boosting military spending?

The man likely to be Germany's next chancellor has found backing for a plan to spend hundreds of billions of euros on defense and infrastructure. Friedrich Merz, who leads the centre-right Christian Democrats, has convinced his likely coalition partners that the so-called 'debt brake,' which limits government borrowing, should be reformed. The parties want to change the constitution to allow a major increase in defense spending to be funded through borrowing.