Starting with tips from intelligence reports about specific targets, agents search the database in what one official described as a "24-7" operation.

But another official described the effort as "a major operation" that involved extensive coordination among Federal agencies across the country, with Washington in charge.

The museum's director, Mikhail Piotrovsky, has described the apparent theft as an inside operation.

Chief Louis described the shootings as "a very slick operation," but declined to give further details.

The army command described its offensive as a "limited preventive operation" to pre-empt a possible militia attack.

A Police spokesman described it as "a neat and clean operation".

Iranian state agencies described Wednesday's attack as a terrorist operation, and a senior official blamed Israel for it.

Two Palestinian factions claimed responsibility for the assault, describing it as a joint operation.

He described the system as a nationwide operation covering all the areas that cellular telephone companies, which concentrate in urban areas, do not cover.

It has been described as a severely undermanned operation that sustained severe casualties in a very short time.