Morgan,

Thank you. Yes it is the Marine Corps Law Enforcement Battalions, which on a quick Google check have an active and reserve component.

Hopefully such formations learn from outside the USA too. The RCMP and the Australian Federal Police (AFP) have considerable UN experience, plus the key European Gendarmerie nations and a few others beyond - India comes to mind, with a variety of para-miltary formations. I am sure they'd be welcome in Northern Ireland too - not on the street though!