Historical clue formulations

• *Done openly — 2021-09-29
• Like cloak-and-dagger operations — 2016-12-30
• Surreptitious — 2015-07-03
• Like some operations — 2013-04-05
• Like C.I.A. operations — 2013-04-01
• Hidden — 2009-10-04
• Hidden from view — 2008-09-22
• Not apparent — 2006-02-08
• Like C.I.A. operations — 2003-05-05