Nine men have been charged with conspiracy to cause explosions in Britain and with preparing for terrorism, West Midlands police say.
The men are aged between 19 and 28. Three are from Cardiff, two from east London and four from Stoke-on-Trent.
Twelve men were arrested in raids co-ordinated by the West Midlands Counter Terrorism Unit on 20 December. Three have been released without charge.
Those charged are accused of conspiring on dates between 1 October and 20 November to cause an explosion.
They are also accused under the Terrorism Act 2006 of engaging in conduct in preparation for acts of terrorism between 1 October and 20 December.
The independent reviewer of British counter-terrorism laws, Lord Carlile, told MPs at the time of the arrests that the allegations were of a "significant" plot.