Expensive military assets such as Britain's new aircraft carriers are vulnerable to cheaply-produced Chinese and Russian missiles, a military think tank has warned.
The Royal United Services Institute (RUSI) said that developing "protective capabilities" for its warships has not been a priority for the Ministry of Defence (MoD).
It added that the advancing capabilities of potential adversaries should now be a matter of "genuine concern".
RUSI warns that a missile costing less than £500,000 could disable Britain’s new £3.1billion HMS Queen Elizabeth:
"China and Russia appear to have focused many (but not all) their efforts on being able to put at risk the key Western assets that are large, few in number and expensive."
A MoD spokesman said: "We keep all threats under constant review and we are confident our new aircraft carrier, and other state-of-the-art equipment, is well protected thanks to defensive systems we have invested in as part of our £178 billion equipment plan."
The reports also highlights the risks brought by the development of cyber and anti-satellite capabilities, which are particularly appealing because they do not require "a large capital investment or the wide-ranging knowledge base needed, for instance, for the development of a new combat aircraft".
However, it said the UK also made extensive military use of space for surveillance, communication, intelligence and navigation, including the control of missiles flying within the atmosphere, creating further vulnerabilities.
The Chinese carried out the test destruction of a satellite in 2007 and since then, there have been numerous reports of Russia seeking to acquire anti-satellite capabilities, including an airborne laser system.
"Space assets are vulnerable to electromagnetic and physical attack that could - for example - destroy or degrade navigation and communication systems," the report said.
The report's co-author Professor Trevor Taylor said:
"UK defence policy prioritises the capability to project force to areas of concern and to deter attacks on British assets and allies."
"The advancing capabilities of potential adversaries in Northern Europe, the Middle East and even East Asia need to be taken into account in reviews of UK defence policy and military tasks, British and NATO approaches to deterrence strategy, and the priorities for UK capability development."