Mocked by colleagues, Cameron argues Britain is safer in EU

By Elizabeth Piper and Kylie MacLellan LONDON (Reuters) - Britain needs the European Union to help fight Islamic State and rebuff a "newly belligerent" Russia, Prime Minister David Cameron said on Monday, making a "patriotic case" for membership that was immediately mocked by a one-time ally. With just over six weeks to go before a referendum, both sides of the debate are sharpening their arguments, with Conservative former London mayor, Boris Johnson, attacking the prime minister for scaremonge