With manned aircraft, carriers are not a cost-effective way to counter insurgents and terrorists, and will face budget cuts in order to fund other, less costly sources of airpower.

CENTERFORSECURITYPOLICY: Where are the carriers?

These include closer co-operation between national intelligence agencies, the creation of an EU counter-terrorism chief, and measures that make it easier to trace terrorists who use mobile phones and e-mail.

ECONOMIST: An explosive relationship | The

Counter-terrorism officers say muscular powers of arrest enable them to disrupt terrorists' networks and their plans to attack, even when there is insufficient evidence to convict them.

ECONOMIST: Chasing al-Qaeda

For one thing those on the front line in counter-terrorism warn that it risks cutting off vital local intelligence and serving as a recruiting sergeant for terrorists.

BBC: NEWS | UK | UK Politics | David Davis speech in full

An unmanned aircraft like N-UCAS solves both these problems at once, providing a cost-effective capability that allows the carriers to find and attack terrorists and insurgents, and also to counter cruise and ballistic missile threats from a survivable distance.

CENTERFORSECURITYPOLICY: Where are the carriers?