The UK will build "up to" 12 new attack submarines, the prime minister will announce, as the government unveils its major defence review on Monday. The new conventionally-armed, nuclear-powered submarines will replace the seven-strong Astute class from the late 2030s onwards.

The UK intends to send a “message to Moscow” with plans to expand its fleet of attack submarines and invest in its nuclear deterrent as part of a new defense strategy to head off the threat posed by Russia.

The PM will also announce £15billion for the UK's nuclear warhead programme as strategic defence review calls for shift to 'war-fighting readiness'