A detailed list, with clips and pointers to the fuller versions on 'Think Defence' a UK blog site and many have a 'Small Wars' theme such as 'Warriors' set in a Bosnia UN peacekeeping mission and better known 'Lawrence of Arabia':http://www.thinkdefence.co.uk/top-25-british-war-films/

The author explains:
the definition of a British War Film is one that is largely British in character. They may have been directed by non-British directors, have non-British actors and may even have been made in Hollywood or elsewhere, but they retain that element of Britishness that we all understand....The judging criteria... it is simply enjoyability for a wet Sunday afternoon in.
My own two favourites are 'Master and Commander', a Napoleonic naval drama, one ship after another with Russell Crowe and 'Zulu'.

There are a number of threads on individual films and one on films in COIN, back in 2010:http://council.smallwarsjournal.com/...ead.php?t=5076

A Kings of War 2010 list:http://kingsofwar.org.uk/2010/02/films/

There is no thread on an American equivalent.