The phrase "war drums" refers to the idea of a possible conflict or battle. It symbolizes the anticipation or preparation for war, typically depicted by the sound of drums used to rally troops and create a sense of urgency. Full definition
I proposed a war strategy game involving war drums to them using these characters, and right off the bat, they thought the idea had merit. (blog.us.playstation.com)
At a time when war drums are thudding, these quiet thoughts are music to the ears. (chicagoreader.com)
The play of sounds, colors, and textures, derived from Japanese woodblock prints and taiko war drums and films ranging from Hayao Miyazaki's fantasias to «Godzilla» and Akira Kurosawa's «Seven Samurai» (the score of which is utilized in one sequence), is a revivifying mélange. (csmonitor.com)