Wiggle on front end

My 2003 taurus has a shimmy in the front end when i brake. It doens’t happen when I’m going along at normal speed or when I make turns. I was wondering if it’s a brake problem and could it be warped rotors?? Car has 140.000 miles on it, we replaced pads and rotors at 65,000 miles. Tires???

warped rotors.