come out swinging
US /kʌm aʊt ˈswɪŋɪŋ/
UK /kʌm aʊt ˈswɪŋɪŋ/

1.
to immediately respond to a situation or argument with great force or aggression
:
•
When he was accused of cheating, he immediately came out swinging, denying all allegations.
•
The new CEO decided to come out swinging with a bold new strategy to turn the company around.