Does resorting to masturbation in Ramadan due to strong urges invalidate the fast, and is it obligatory to complete it?

If semen is ejaculated during fasting, the fast is invalidated and that day must be made up, while refraining from eating for the rest of the day. However, if ejaculation does not occur, the fast is not invalidated, but repentance from this forbidden habit is obligatory in all cases.