This article is more than 9 years old

This article is more than 9 years old

The government has decided that Britain will no longer be able to mount military operations on the scale of the 2003 invasion of Iraq and the deployment in Afghanistan's Helmand province, it emerged today as David Cameron unveiled the details of the strategic defence and security review.

The prime minister insisted that the coalition was protecting Britain's future security today as he confirmed cuts to the armed forces as part of an 8% real-terms fall in the defence budget by 2015.

But it emerged that the planned cuts to military personnel mean that the largest overseas deployment over the next decade will consist of 30,000 troops – two thirds of the number of British troops that took part in the invasion of Iraq.

This suggests that Britain will also no longer be able to sustain the sort of long-term campaign it is fighting in Helmand when combat British troops end their mission in Afghanistan in 2015. A future "enduring stabilisation operation" will consist of 6,500 troops – lower than the numbers currently in Afghanistan.

The prime minister, who announced that the army will be cut to 95,000 by 2015, said that Britain should focus more attention on the causes of conflict to reduce the high costs of "just dealing with the consequences" of failed states.

Cameron's announcement marks the end of Tony Blair's concept of "liberal interventionism", first set out in his 1999 Chicago speech during the Kosovo crisis.

Outlining the outcome of the review in a statement to the Commons this afternoon, Cameron sought to allay fears by insisting that, despite the cuts, Britain would still have the fourth largest military budget in the world and would meet the Nato target of spending 2% of GDP on defence.

The prime minister insisted that the review was not just a cost-saving exercise to "get to grips with the biggest budget deficit in post war history", but also about taking the "right decisions" to protect Britain's national security in the years ahead.

Measures announced today to scale down the budget included:

• A cut of 25,000 staff in the Ministry of Defence by 2015, the disposal of "unnecessary" assets, and a getting to grips with procurement.

• Cancelling the Nimrod reconnaissance aircraft programme.

• Naval manpower to be cut by 5,000 to 30,000 by 2015 and the total number of frigates and destroyers to drop from 23 to 19 by 2020.

• The government to retire the Harrier jump jet and reduce RAF manpower by 5,000 to 33,000 by 2015.

• Tanks to be reduced by 40%.

• Half a billion pounds allocated to a national cyber security programme to counter unconventional threats of the future.

Outlining the backdrop to the cuts, Cameron said the coalition government had inherited a £38bn black hole in future defence plans – bigger than the entire annual defence budget of £33bn.

He said Britain would still punch "above its weight in the world" but needed to be "more thoughtful, more strategic and more co-ordinated in the way we advance our interests and protect our national security".

He added: "This review sets out a step change in the way we protect this country's security interests."

Cameron promised there would be "no cuts whatsoever" in support for troops in Afghanistan after taking the advice of the defence chiefs who had told him a cut could affect operations in Afghanistan. In fact, the troops in Afghanistan will get better equipment, he said.

Cameron also used his speech to confirm that the crucial decision about whether to replace Britain's nuclear deterrent – a fault line between the Tories and Liberal Democrats – would not be taken until after the next general election, which will be no later than 2015.

Instead, the life of the Vanguard class of submarines that carry the Trident system will be extended so that the final go-ahead for new submarines need not be given until "about 2016".

Cameron also confirmed the decision to retire the Harrier jump jet – a decision that, along with the retirement of the HMS Ark Royal, means that the UK will be without an aircraft carrier carrying jets until 2020.

Cameron said: "This is not simply a cost-saving exercise to get to grips with the biggest budget deficit in post-war history, it is about taking the right decisions to protect our national security in the years ahead. But the two are not separate. Our national security depends on our economic strength and vice versa. As our national security is a priority so defence and security budgets will contribute to deficit reduction on a lower scale than most other departments."

Cameron told MPs that the defence review has been led from the top and will be repeated every five years.

Outlining his vision for the future, he added: "From a Ministry of Defence that is too big, too inefficient and too overspent to a department that is smaller, smarter, and more responsible in its spending," he said.

"From a strategy over-reliant on military intervention to a higher priority for conflict prevention. From concentrating on conventional threats to a new focus on unconventional threats. And from armed forces that are overstretched, under-equipped and deployed too often without appropriate planning to the most professional and most flexible modern forces in the world, fully equipped for the challenges of the future."

The Lib Dems hailed the coalition's decision to reduce the number of warheads carried by Trident submarines.

Lady Williams, the Lib Dem peer, said the decision had come at a critical time for multilateral disarmament.

"The Start II treaty is the first agreement between the United States and Russia since Start I to cut their nuclear arsenals substantially. The treaty is now languishing in the US Senate, awaiting ratification. Ambitious plans to control the production of fissile materials are in suspension. The comprehensive nuclear test ban treaty is a distant aspiration. So this significant step by the UK government could help to remove the log-jam."

Ed Miliband, the Labour leader, told Cameron that the strategy was "not credible" and a "missed opportunity".

Miliband was greeted with shouts of "apologise" from Tory benches as he stood to respond.

He said: "We will help the prime minister and his government as they seek to do what is best for our nation's security. But I do have to tell him many people believe this review is a profound missed opportunity.

"It is a spending review dressed up as a defence review, it has been chaotically conducted, it has been hastily prepared and it is simply not credible as a strategic blueprint for our future defence needs."

Miliband also said the statement had been extensively leaked in a process he described as a "complete shambles"