"This is the biggest security operation in our peacetime history, bar none, and we are leaving nothing to chance."
Suicide attacks on London on July 7, 2005, the day after London was awarded the Games, killed 52 people. This year the Games will mark the 40th anniversary of the 1972 Munich massacre, when 11 Israeli Olympic team members were killed by Palestinian militants.
ARCHERY WORLD RECORD
Although no medals will be awarded until Saturday, the women's football tournament started on Wednesday, and on Friday South Korean archers set the first world records of the Games.
Their three-man team totalled 2,087 points at Lord's Cricket Ground as Im Dong-hyun, who suffers from severe myopia and just aims at "a blob of yellow colour", broke his own 72-arrow world record with a score of 699 out of a possible 720.
Image: Flags of various countries hang in the foreground as actors perform during the Opening Ceremony at the 2012 Summer Olympics, Friday, July 27, 2012, in London.