Many issues that an individual or a society faces can be morally ambigious. Resistance and terrorism are often morally ambiguous.
A comic book that will soon become a movie is V for Vendetta by Alan Moore and David Lloyd. The comic book explores how oppression causes liberation and resistance movement to develop, and often the latter commit atrocities and abhorrent acts in the name of good causes. This is a fault both sides may fall in, and hence there is no moral high ground for one side over the other.
It is sometimes ironic how one party in a conflict becomes exactly what they hate in the other side in the name of 'good', 'justice', 'freedom' or 'democracy'.