US officials have closed in on the man believed to be at the centre of a huge leak of highly classified Pentagon documents, after days of investigation. The leak forced officials at the highest levels of the United States Department of Defense into the online worlds of gamers, meme lords and their leagues of followers. The full scope of the 50-plus documents at the centre of this leak is not yet clear, but it represents one of the worst breaches of US national security this century. The documents that have attracted the most attention include details from US military briefings...