A reader writes:

After the defeat and obliteration of the Papal states in 1870 the Holy See lost the Papal Army. When the See was restored to an independent state in the Lateran treaty of 1929 (with 1985 amendments), the authority of the Pope to have anything other than the Swiss guards was clipped.
Moreover, Article 24 of the Lateran treaty prohibits the Holy See from either taking sides or even taking part in any “temporal rivalries”. That’s one reason, among many, the Holy See is observer status only at the UN.
Article 24
In regard to the sovereignty appertaining to it also in international matters, the Holy See declares that it desires to take, and shall take, no part in any temporal rivalries between other States, nor in any international congresses called to settle such matters, save and except in the event of such parties making a mutual appeal to the pacific mission of the Holy See, the latter reserving in any event the right of exercising its moral and spiritual power.
The Vatican City shall, therefore, be invariably and in every event considered as neutral and inviolable territory.

He adds in a follow-up:

The 1505 treaty that allows the Swiss Guard to come into Vatican City and defend the Pope limits them to only those specific tasks, something that was repeated in the Treaty of Westphalia in 1648. Mind you, this was at a time when these were considered the most ruthless, cunning and best warriors of their time. But the prohibition stuck.
When Tom Clancy wrote about just such a “Swiss Guard Peace Keepers” plan, he included the need to amend Westphalia.

Me: These are good practical objections. But we’re trying to get the Japanese to change their constitution and hop onto the Security Council. Treaties can be amended. And, Derb, Swiss guards can be trained-up.