The British government says it will put armed sky marshals on some passenger planes.
In a joint statement Sunday, the departments responsible for transport and fighting terrorism in Britain said security is constantly under review and it is essential to take all "reasonable" steps to deter terrorist activities.
It also said the marshals would be deployed "where appropriate." No further details were given.
Today's announcement came one week after Washington raised the terror alert in the United States to its second-highest level, warning that al-Qaida continues to consider using aircraft as a weapon.
U.S. Homeland Security Secretary Tom Ridge says despite an event-free Christmas holiday, the risk of terrorism remains high.
Secretary Ridge told CNN on Saturday that he is relieved every day nothing happens.
He said the cancellation last week of Air France flights from Paris to Los Angeles was the result of "great collaboration" between the U.S. and French governments.
The flights were halted Wednesday and Thursday because of a possible terrorist threat. They resumed without incident Friday.