Ministers revealed today that they will fork out for 18,000 troops to provide Olympic security.
They explained the decision by saying that they would "leave nothing to chance."
Culture Secretary Jeremy Hunt said the 1,200 servicemen and women put on 48 hours notice last week will be deployed in the wake of the G4S security scandal.
The extra military involvement comes on top of the additional 3,500 troops drafted in a fortnight ago as the "humiliating shambles" created by private firm G4S's failure to supply enough guards emerged.
A further contingency force of 1,000 troops is ready to step in if there is any increase in the security threat level.
It is not clear whether pressure from the United States, which has reportedly demanded a hefty security presence in London, was behind the additional deployments.