Why an expansion of Nato's role has divided the Dutch

In the Netherlands the issue could yet bring down the government; in Britain it has hardly been discussed.

Nato's planned expansion to the south of Afghanistan opens a new and dangerous chapter in Western involvement in a lawless country and, for the politicians and the military, the stakes are high. Nato's preparations have been held up for weeks as first the Dutch cabinet, and now the country's parliament, debate whether to deploy around 1,400 soldiers. Politicians there are questioning whether a peace-keeping mission can operate in such a treacherous environment.

It all seems so different from the aftermath of the attacks on the twin towers in 2001, when European nations were falling over each other to take part in the US mission against the Taliban, complaining bitterly when their offers were spurned.

Since then Europe's appetite for involvement has faded as disputes over Iraq divided the alliance. That has often left Nato pleading for troops, helicopters, and other equipment.

Nato's Isaf (International Security Assistance Force) mission currently numbers about 9,200 troops including 1,100 Britons. Initially restricted to the capital Kabul, the alliance has spread its efforts to around half of Afghanistan through so-called Provincial Reconstruction Teams (PRTs) designed to bring regional stability.

The next stage foresees an expansion to the south with the creation of at least four new PRTs, meaning Nato will operate in three-quarters of Afghanistan.

For Britain this will result in a significant new commitment. The UK plans to deploy the Headquarters Group of the Allied Rapid Reaction Corps to lead Isaf from May involving around 900 personnel. It will also establish a UK-led PRT in the province of Helmand, in southern Afghanistan, probably requiring more than 2,000 soldiers. In total British troop numbers are likely to rise to around 4,000.

The Dutch already have 1,200 soldiers in Afghanistan and the new deployment would see a further 1,400. The government is under mounting pressure, with Nato officials arguing that any failure by the Dutch would confirm suspicions in Washington that most European nations are lily-livered. But in the Netherlands the debate has crystallised around the extent to which the mission could get embroiled in the US-led "war on terror".

The US has a force of around 8,500, known as Operation Enduring Freedom, in Afghanistan tracking down rogue al-Qa'ida and Taliban elements.

One Dutch objection has now been largely overcome after assurances were given that any prisoners taken by its Nato force would not face the death penalty or be sent to Guantanamo Bay. A more far-reaching worry is that Isaf's mission will become confused as it extends into more dangerous territory. The Pentagon has long wanted to create a joint command for the two missions. The latest plans fall short of that but they would make Isaf's deputy commander a US officer from Enduring Freedom.

In the Netherlands, the issue is particularly sensitive because of the failure of Dutch UN peacekeepers to prevent the Srebrenica massacre in 1995.

Lousewies van der Laan, deputy leader of the D66 party which is part of the ruling Dutch coalition, argues: "If you are busy fighting the Taliban and al-Qa'ida, how do you have the space to win hearts and minds by building schools and hospitals?"