The fight that never was

Having heard a loud guttural yell, I rushed to the kitchen to find my Cassie kitty perched on the stool in the window nose-to-nose with my neighbor's white cat. By the time I retrieved my camera, both had retreated.
Cassie continues to watch the intruder.
But eventually both cats tire of the confrontation.
As I walk away, I hear a commotion and turn to see Cassie lunging at the cat against the window. After a few loud thumps and realizing that glass and screen separate the two, the other cat retreated and jumped over the fence.