Britain has introduced a new security alert system that currently ranks the terrorist threat to the country as "severe" and says an attack is highly likely.
It was the first time the government had published such information. Until now, it has argued that doing so would cause unnecessary alarm.
But faced with growing criticism that it was failing to spell out the threat from groups like al-Qaeda, the government has decided to follow the lead of other countries and introduce a graded alert system.
The new system has five levels ranging from "low" (attack unlikely) to "critical" (attack expected imminently), and is similar to the one used in the United States for the past four years, although, unlike the US model, it is not colour-coded.
"Severe" is the second highest level. The threat level was posted on a new website - www.intelligence.gov.uk - and on the Home Office (interior ministry) and security service sites.
Analysts say the decision to publish is part of an effort - not only by the government but also by the two security services MI5 and MI6 - to be seen as more accountable.
Until now, Britain operated a more complex seven-level system and never told the public what the level was.