Britain's ability to project its power and influence internationally will fall as a result of defence cuts, a thinktank has said.
The International Institute of Strategic Studies' annual The Military Balance publication, which assesses the defence capabilities of countries around the world, offered a scathing assessment of last year's strategic defence and security review (SDSR).
It said that the review had reduced Britain's long-term ability to deploy in operations outside Europe by between one-quarter and one-third.
"The SDSR was essentially a budget-cutting exercise which degenerated into inter-service rivalry as each of the three military branches lobbied the prime minister and the Treasury in support of what they claimed were vital capacities," the IISS said.
"The resultant contraction in military capacity will reduce the nation's ability to project military power and influence internationally."
Speaking at the publication's launch in central London, Brigadier Ben Barry of the IISS said Britain has not fallen down the "league table" compared to other Nato states.
"Compared with western forces, Britain will retain its rough position in the league table because otherwise countries are subject to similar pressures," Brig Barry said.
He said that the real test would come after Britain's commitment in Afghanistan begins to draw down. UK troops are set to cease combat roles in the country by 2015.
"Will there be the investment in equipment and particularly in training to enable the armed forces to recreate their cutting edge of all-spectrum warfare across land, sea and air?" Brig Barry said.
"There is the proposition that this requires real sustained investment in the British defence budget after 2015. If that investment is not made for whatever reason, including the failure of the UK economy to bounce back, it is highly probably more significant and powerful reductions would have to be made."
Most Nato states are already cutting their defence budgets or are about to start doing so by a comparable amount, meaning Britain becomes part of a much broader trend.
The Military Balance's main theme was a shift in military spending from the west's shrinking defence budgets to the booming defence economies of developing countries, especially in the Far East.
"Western states' defence budgets are under pressure and their military procurement is constrained. But in other regions - notably Asia and the Middle East - military spending and arms acquisitions are booming," the IISS' John Chipman said.
"There is persuasive evidence that a global redistribution of military power is under way."