An armed police officer (R) stands guard with police officers outside the Houses of Parliament where lawmakers are expected to vote in favour of joining air strikes against Islamic State (IS) militants in central London on 26 September, 2014. British Prime Minister David Cameron warned that military action against Islamic State (IS) militants could last for "years" Friday as he urged lawmakers to back joining US-led air strikes in Iraq but not in Syria. Kicking off a crunch debate in the House of Commons, Cameron said the "hallmarks" of the campaign would be "patience and persistence, not shock and awe". AFP PHOTO / JUSTIN TALLIS (Photo credit should read JUSTIN TALLIS/AFP/Getty Images)
