In the news

Genuine question - has the UK ever been directly in danger of attack from the Taliban? Why are we there?

"Every death and every injury reminds us of the human cost paid by our armed forces to keep our country safe," he said, at the start of Prime Ministers' Questions.

http://www.bbc.co.uk/news/uk-17282903

Yes of course. There is nothing* to stop them, for example, building a small navy in a safe haven in Afghanistan and then sailing over here, up the Thames ** and attacking London.

*other than it's landlocked

**must make sure they can get under that Tower bridge as I doubt they'll open it for them