[psychopomp]

The enemy of my enemy is my friend.

[justinclift]

Alternatively (perhaps additionally), if you want to pin a false flag operation on someone they're probably your top choice.

[majestic5762]

Exactly

[skipkey]

The enemy of my enemy is my enemy’s enemy. Nothing more, nothing less.

- Howard Tayler, Schlock Mercenary

[teddyh]

Maxim 29: https://www.ovalkwiki.com/index.php?title=The_Seventy_Maxims...