help needed: iphone 5C and windows

Hello! I am trying to transfer about 4,000 photos from my iPhone 5C to a USB drive (it has enough storage). I'm trying to do this on my computer, running Windows 8.1, but it wants me to import the photos to the computer first. However, my laptop is absolutely terrible and I know if I try importing the photos there first it will crash. Is there any way I can transfer the photos directly from my phone to the USB without having to import them to the computer?