Calling for root-and-branch reform of Nato and a new pact drawing the US, Nato and the European Union together in a "grand strategy" to tackle the challenges of an increasingly brutal world, the former armed forces chiefs from the US, Britain, Germany, France and the Netherlands insist that a "first strike" nuclear option remains an "indispensable instrument" since there is "simply no realistic prospect of a nuclear-free world".

The manifesto has been written following discussions with active commanders and policymakers, many of whom are unable or unwilling to publicly air their views. It has been presented to the Pentagon in Washington and to Nato's secretary general, Jaap de Hoop Scheffer, over the past 10 days. The proposals are likely to be discussed at a Nato summit in Bucharest in April.

"The risk of further [nuclear] proliferation is imminent and, with it, the danger that nuclear war fighting, albeit limited in scope, might become possible," the authors argued in the 150-page blueprint for urgent reform of western military strategy and structures. "The first use of nuclear weapons must remain in the quiver of escalation as the ultimate instrument to prevent the use of weapons of mass destruction."

The authors - General John Shalikashvili, the former chairman of the US joint chiefs of staff and Nato's ex-supreme commander in Europe, General Klaus Naumann, Germany's former top soldier and ex-chairman of Nato's military committee, General Henk van den Breemen, a former Dutch chief of staff, Admiral Jacques Lanxade, a former French chief of staff, and Lord Inge, field marshal and ex-chief of the general staff and the defence staff in the UK - paint an alarming picture of the threats and challenges confronting the west in the post-9/11 world and deliver a withering verdict on the ability to cope.

The five commanders argue that the west's values and way of life are under threat, but the west is struggling to summon the will to defend them. The key threats are:

· Political fanaticism and religious fundamentalism.

· The "dark side" of globalisation, meaning international terrorism, organised crime and the spread of weapons of mass destruction.

· Climate change and energy security, entailing a contest for resources and potential "environmental" migration on a mass scale.

· The weakening of the nation state as well as of organisations such as the UN, Nato and the EU.

To prevail, the generals call for an overhaul of Nato decision-taking methods, a new "directorate" of US, European and Nato leaders to respond rapidly to crises, and an end to EU "obstruction" of and rivalry with Nato. Among the most radical changes demanded are:

· A shift from consensus decision-taking in Nato bodies to majority voting, meaning faster action through an end to national vetoes.

· The abolition of national caveats in Nato operations of the kind that plague the Afghan campaign.

· No role in decision-taking on Nato operations for alliance members who are not taking part in the operations.

· The use of force without UN security council authorisation when "immediate action is needed to protect large numbers of human beings".

In the wake of the latest row over military performance in Afghanistan, touched off when the US defence secretary, Robert Gates, said some allies could not conduct counter-insurgency, the five senior figures at the heart of the western military establishment also declare that Nato's future is on the line in Helmand province.

"Nato's credibility is at stake in Afghanistan," said Van den Breemen.

"Nato is at a juncture and runs the risk of failure," according to the blueprint.

Naumann delivered a blistering attack on his own country's performance in Afghanistan. "The time has come for Germany to decide if it wants to be a reliable partner." By insisting on "special rules" for its forces in Afghanistan, the Merkel government in Berlin was contributing to "the dissolution of Nato".

Ron Asmus, head of the German Marshall Fund thinktank in Brussels and a former senior US state department official, described the manifesto as "a wake-up call". "This report means that the core of the Nato establishment is saying we're in trouble, that the west is adrift and not facing up to the challenges."

Naumann conceded that the plan's retention of the nuclear first strike option was "controversial" even among the five authors. Inge argued that "to tie our hands on first use or no first use removes a huge plank of deterrence".

Reserving the right to initiate nuclear attack was a central element of the west's cold war strategy in defeating the Soviet Union. Critics argue that what was a productive instrument to face down a nuclear superpower is no longer appropriate.

Robert Cooper, an influential shaper of European foreign and security policy in Brussels, said he was "puzzled".

"Maybe we are going to use nuclear weapons before anyone else, but I'd be wary of saying it out loud."

Another senior EU official said Nato needed to "rethink its nuclear posture because the nuclear non-proliferation regime is under enormous pressure".

Naumann suggested the threat of nuclear attack was a counsel of desperation. "Proliferation is spreading and we have not too many options to stop it. We don't know how to deal with this."

Nato needed to show "there is a big stick that we might have to use if there is no other option", he said.

The Authors:

John Shalikashvili

The US's top soldier under Bill Clinton and former Nato commander in Europe, Shalikashvili was born in Warsaw of Georgian parents and emigrated to the US at the height of Stalinism in 1952. He became the first immigrant to the US to rise to become a four-star general. He commanded Operation Provide Comfort in northern Iraq at the end of the first Gulf war, then became Saceur, Nato's supreme allied commander in Europe, before Clinton appointed him chairman of the joint chiefs in 1993, a position he held until his retirement in 1997.

Klaus Naumann

Viewed as one of Germany's and Nato's top military strategists in the 90s, Naumann served as his country's armed forces commander from 1991 to 1996 when he became chairman of Nato's military committee. On his watch, Germany overcame its post-WWII taboo about combat operations, with the Luftwaffe taking to the skies for the first time since 1945 in the Nato air campaign against Serbia.

Lord Inge

Field Marshal Peter Inge is one of Britain's top officers, serving as chief of the general staff in 1992-94, then chief of the defence staff in 1994-97. He also served on the Butler inquiry into Saddam Hussein's weapons of mass destruction and British intelligence.

Henk van den Breemen

An accomplished organist who has played at Westminster Abbey, Van den Breemen is the former Dutch chief of staff.

Jacques Lanxade

A French admiral and former navy chief who was also chief of the French defence staff.