Britain's international terrorism threat level was lowered from severe to substantial today, interior minister Theresa May said, a year ahead of the London Olympics.
Substantial is the third highest level, meaning a terrorist attack is a strong possibility and might well occur without further warning.
"The change in the threat level to substantial does not mean the overall threat has gone away - there remains a real and serious threat against the United Kingdom and I would ask the public to remain vigilant," she said in a statement.
The decision comes a year ahead of the Olympics, predicted to be Britain's biggest peacetime security operation.
The country is facing several potential threats, one of the most high-profile being from al-Qaeda after Britain's support of US military operations in Afghanistan and Iraq.
The threat level has been severe since January 2010, after a Nigerian was accused of trying to blow up a transatlantic flight on Christmas Day with a bomb in his underwear. Severe means a militant attack is considered highly likely.
The decision to lower the level was made by the independent Joint Terrorism Analysis Centre (JTAC), regarding factors such as capability, intent and timescale.