Star Trek: Captain's Chair · Board game rules
Who chooses who performs Attack operations?
Quick answer
The active player (the one whose card it is) resolves the ATTACK operation; if it forces the opponent to choose between effects, the opponent must pick one they can fully resolve.
Details
An ATTACK operation is any operation that negatively affects your opponent, and it's the player who plays or activates that card who performs/resolves it — the presence of "ATTACK" doesn't change who takes the action or whether it costs a ⚡ action [p.10 — ATTACKING OPERATIONS]. If the ATTACK operation includes a choice ("either A or B") that the opponent must make, they are required to choose an option they are able to fully resolve [p.10 — ATTACKING OPERATIONS].
This ties into the general Force rule: when an effect forces your opponent to do something, they must resolve the indicated effect, but any choice within that effect (e.g., which of their own cards to dismiss) belongs to them. In contrast, if the attacker's card specifies a choice like "dismiss an opponent's SHIP," it is the attacker who picks the target, not the opponent [p.30 — FORCE].
Watch out: Don't confuse "who resolves the operation" (always the attacking player, on their turn) with "who makes internal choices within a forced effect" — that depends on the exact wording ("dismiss an opponent's X" = attacker's choice; "force opponent to dismiss an X" = opponent's choice, but only among options they can fully complete) [p.30 — FORCE].