MI-5 to Put All 4K Agents on Olympic Watch Called biggest security operation in England since WWII By Mark Russell, Newser Staff Posted Mar 26, 2012 4:35 AM CDT 1 comment Comments British Transport police officers provide security at Stratford Underground station, in east London, Wednesday, Jan. 18, 2012. (AP Photo/Lefteris Pitarakis) (Newser) – The London Olympics looks to be the biggest security operation in England since World War II, with nearly all 3,800 of Britain's MI-5 agents staff mobilized in the capital against potential terrorist attacks, reports the Independent. With 540,000 people and 120 heads of state expected to attend the international sports extravaganza in July and August, MI-5 estimates it will spend up to $1.58 billion on security for the Olympics. In addition, Britain's foreign security agency MI-6 and its electronic listening division GCHQ will be involved in security, along with 13,500 military personnel. There will even be surface-to-air missiles placed around London.