The question of why O'Brien was going over security arrangements with aliens is never explained. Kira leans over a railing in a creepy manner. O'Brien is kept away from the planning of a peace conference. O'Brien thinks Keiko tried to poison him and becomes increasingly paranoid about his comrades strange beahaviour. After season 1's 'Dramatis Personae' and what happened to him in the TNG ep 'Power Play', you can understand why.
O'Brien eventually goes on the run and the ep gets ridiculous. O'Brien starts ranting at an Admiral as he fears whatever alien influence has overtaken his comrades has spread throughout Starfleet (well seeing as it happened once before in the TNG ep 'Conspiracy', he was right to worry). Then we get the idiot ending. This was disapointing as it was full of bad, bad bad acting and O'Brien seemed bored.
"I wish I could tell you who they are."
"All I could think of as I looked at her was that this was not my Keiko."