Deck the jails with jihadis........
It is understood that the plans for the alleged attacks were at an advanced stage and involved 'multiple' locations.
West Midlands Police said in a statement: 'All were arrested at or near their home addresses, with the exception of one suspect from Stoke who was at a domestic property in Birmingham.
'Searches are now being conducted at the home addresses, plus the address in Birmingham and another residence in London.
'The suspects will be held at police stations in central London, the North West and the West Midlands.'
The police statement said five of the suspects were from Cardiff, four were from Stoke-on-Trent and three were from London, including the 17-year-old.
The operation is being led by Metropolitan Police Deputy Assistant Commissioner Stuart Osborne, the Senior National Co-ordinator Terrorist Investigations, and is being coordinated from the West Midlands Counter-Terrorism Unit.