Do not, 'under any circumstances', open that door. = 'Under no circumstances' are you to open that door. [=no matter what happens, do not open that door]
Due to 'circumstances beyond our control' [=things that have happened that we cannot change or influence], the flight is canceled.
She says that her client is 'a victim of circumstance' and should not be blamed for the accident.
(..) I'm not arguing with you about that. That would be my advice as well. Yes, absolutely. But, um- Yes, and I can understand your feeling under the circumstances. Absolutely. Yes, that is quite right. But I must say to you, sir, whatever your feelings are, you must not call me here... (..)1975 The Return of the Pink Panther