system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:why does the Swiss army guard the Vatican?

I was told that it was historical reason. If so why do they guard the Vatican today and why doesn't the Italian army guard?
gpt
The short answer is that the Swiss Guard are mercenaries. The Vatican has continued to pay to extend the Swiss Guard contract for over 500 years. At this point it's mostly just tradition, however, those guards are well trained.