Once a creature attacks (or enters the battlefield attacking), it remains an attacking creature for the rest of the combat phase unless it's removed from combat (C.R. 506.4, 511.3; see also C.R. 508.1k). For example, Reconnaissance's ability can target any "attacking creature you control", even after it has assigned combat damage, and even during the end of combat step (C.R. 115.1c). See also this thread and this thread.
When exactly a creature stops being considered an "attacking creature"?