system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] What if the prime minister had believed the minister of Magic

Assuming the minister of magic is nonetheless wiser to the prime minister believing him. The prime minister in this scenario wants to help.
gpt
The most he could/would do, I'd imagine, would be to swear a handful of SAS troops to secrecy and put them to work alongside the Aurors.  No reason to cause mass panic, after all.  
It'd have dubious effectiveness, though.  Tom Riddle most likely knows what firearms/grenades are, having grown up like Harry.  After an engagement or two with Death Eaters, the game would be up, and a modified inertia charm would make firearms useless.