If there were an Academy Award for the best profanity laden insults in a film, In the Loop would be the winner hands down. 
There are more barbs thrown in this movie than any other I can remember. But they are wickedly written and perfectly delivered in one of the most taut political comedies I have ever seen. You really have to listen to the dialogue and keep up with a fast paced story. It is set in the British and US diplomatic circles and concerns a rush to war somewhere in the Middle East precipitated by an off hand remark made by British Secretary of State for International Development, Simon Foster. He is on a talk show discussing aid and mentions a “war on disease,” when the interviewer asks him out of the blue if he is for war. He is thrown and answers that war is “unforeseeable” which is immediately spun by those who want a war as the Prime Minister endorsing the idea. The Americans jump on it, too, with State Department hawks and doves each trying to use him to push their aims. Next thing he knows he is in Washington.
The inside political wrangling that goes on on both sides of the pond is hilarious and frankly quite scary. Intel is leaked to the press, important evidence redacted, stories spun, and arms twisted. The farce leads finally to the UN where a behind the scenes testosterone duel plays out with milk-toast Secretary Foster used, abused and tossed to the side. Tom Hollander (Pirates of the Caribbean and Pride & Prejudice) plays Foster with a wonderful deer in the headlights demeanor throughout. And the rest of the wacked-out ensemble cast are top notch. James Gandolfini is perfect as the dovish US General trying to avert sending his boys to die. Anna Chulmsky (remember her from My Girl with McCauley Culkin?) plays a very ambitious assistant to one of the head honchos at the US State Department and her internal paper about the pros and cons of war becomes a key part of the skirmishing. Every single person in this story is looking out for themselves first and foremost as they take their countries towards war. It is a very serious subject but it is absolutely hilarious. If you can see it now, do. Otherwise, as soon as it is out on DVD, buy it. It isn’t like anything else out there and may be one of the best of 2009.