WHEN does a just cause become unjust? When do the lines blur so much that the endless war on terror becomes an act of terrorism itself?

That is what Andrew Niccol's Good Kill explores.

The film, starring Ethan Hawke, is about the fighter pilots who have downed their jets to 'battle' the Taliban 7,000 miles away from the war zone in an air conditioned room in Las Vegas.

Delving into the world of controversial drone warfare, Good Kill reflects on real events which has seen the use of unmanned aircraft intensify quickly since 9/11.

Unseen from 10,000ft above their targets, the film focuses on the psychological impact on the people who carry out these kill orders using just a joystick – as if it were a computer game.

The loss of innocent life to take out 'high value targets' is masked behind phrases like 'proportionate'.

And the impact of the explosion can be seen but not heard creating an eerie sense detachment from the terrible act, which is subtle and yet really powerful on screen.

Good Kill is shocking, thought provoking and quickly makes its mark making you wonder what you would do in this all-too-real situation.

Credit also goes to Niccol, who was behind Gattaca and The Truman Show, for not over-stylising the film and letting the subject matter speak for itself.

Hawke is excellent as the former fighter pilot struggling to cope with the moral implications of what he is doing.

But Bruce Greenwood steals the show as Hawke's cool, calm commander who supports his team and shares their doubts but whose hands are just as tied from orders from above.