Does deleting a photo from iPhone delete it from iCloud?

Is this not possible to answer with Yes or No? I´ve tried to find the correct answer, but it´s just one big mass of waffling on!

If I delete the image/video file on my iPhone, will it remain in my iCloud storage until I tell it to delete it from there too, or does it SYNC it continuously with my iPhone so it´s gone?

I don´t use iCloud as I always download the photos to an external drive, so I can´t test it.