Britain's defence plans are inadequate to address a dramatic rise in global security threats and a challenge from Russia on Europe's doorstep, a committee of lawmakers said on Tuesday, warning the country risked retreating into isolation.

Under plans set out by the Conservative-led coalition government shortly after it took office in 2010, Britain has cut defence spending by around 8 percent in real terms and shrunk the size of the armed forces by around one sixth.

Parliament's Defence Committee said those plans were "no longer adequate" as they assumed Britain would not need 'Cold War' capacities to engage in state-on-state conflict, and troops would only be deployed long-term in one country at a time.

"The UK's current defence assumptions are not sufficient for this changed environment ... Now there is a requirement to support stability in a dozen different theatres simultaneously, and to engage with both unconventional and conventional threats," the committee said in a report published on Tuesday.

"For the first time in twenty years, an advanced military state has challenged the borders of European nations, and the security challenges in the Middle East, Africa, and South Asia have increased dramatically in scale and complexity ... The UK cannot afford to ignore these challenges and retreat to isolation."

Both Britain's main political parties have committed to holding a defence review if they are in government after a close-fought national election on May 7.

The committee said a failure by Britain to continue to commit to NATO's target of spending 2 percent of gross domestic product on defence would undermine the alliance and have an "extremely damaging" impact on Britain's credibility as a military ally.

Maritime surveillance was a "crucial gap" in Britain's capabilities which must be rebuilt alongside things such as training in nuclear, biological, chemical and radiological warfare, the committee said. New capabilities to respond to threats such as cyber attacks also needed developing, it said.

"It is vital to rethink the fundamental assumptions of our defence planning, if we are to help arrest the descent into chaos, which threatens to spread from the Western Mediterranean to the Black Sea," the committee warned.

reuters.com