"Walk softly and carry a big stick."
Attempt peaceful negotiations while also being prepared for confrontation by displaying one's power, especially elements of force. The phrase is a variation on "speak softly and carry a big stick," a phrase popularized by US President Theodore Roosevelt in a 1903 speech.
https://idioms.thefreedictionary.com/walk+softly+and+carry+a+big+stick#:~:text=walk%20softly%20and%20carry%20a%20big%20stick%20Attempt,US%20President%20Theodore%20Roosevelt%20in%20a%201903%20speech.
(There are other variations of it such as Walk Softly and Carry a Big Book. It indeed is "speak softly" in Roosevelt's speech. Thanks for the upvote, Abby! :).