The West wants to use an Afghanistan meeting on Monday to signal enduring support for Kabul as allied troops go home, but economic downturn in Europe and crises with Pakistan and Iran could stir doubts about Western resolve.

The goal is to leave behind an Afghan government strong enough to escape the fate of its Soviet-era predecessor, which collapsed in 1992 in a civil war. The country's allies are preparing increasingly for a scenario in which there is no peace settlement with the Taliban before most foreign combat troops leave in 2014.

Hosts Germany sought to signal Western staying power as the gathering of dozens of foreign ministers opened in the German city of Bonn.

We send a clear message to the people of Afghanistan: We will not leave you on your own. We will not leave you in the lurch, German Foreign Minister Guido Westerwelle told the opening session of the conference.

Ten years after a similar conference held to rebuild Afghanistan following the September 11 attacks and the toppling of the Taliban government, there is no shortage of worries on the horizon, in particular about the Afghan government's ability to provide security for its own people.

But addressing matters such as how to share out the funding for the still-fledgling Afghan police and army, and how to tackle problems of governance and corruption, may have to compete for attention with brewing confrontations pitting Washington against Pakistan and Iran, two of Afghanistan's most influential neighbours.

A RETURN TO CIVIL WAR?

Pakistan boycotted the meeting after NATO aircraft killed 24 of its soldiers on the border with Afghanistan in a November 26 attack the alliance called a tragic accident.

Some in the West are still hoping Pakistan will use its influence to deliver the Afghan Taliban, whose leadership Washington says is based in Pakistan, to peace talks.

But with embryonic contacts with the Taliban so far yielding nothing, and the government in Kabul unable to provide security and economic development, the risk is that the withdrawal of foreign troops will plunge Afghanistan back into civil war. Renewed strife might also stir more violence over the border in Pakistan, fighting its own Islamist insurgency.

Iran's confrontation with the West over its nuclear programme could also bleed into the war in Afghanistan.

There is potentially a perfect storm of problems lying ahead for Afghanistan, said Sajjan Gohel, international security director at the Asia Pacific Foundation in London.

Afghanistan's security is intrinsically tied to Pakistan. If the problems inside Pakistan worsen, that will have a detrimental impact on Afghanistan. The continuing freefall in relations between the U.S. and Pakistan makes the situation even more precarious.

If relations between the West and Iran also worsen that may be utilised by the clerical regime (in Tehran) to cause problems in Afghanistan.

A U.S. official travelling to Bonn with U.S. Secretary of State Hillary Clinton tried to play down Pakistan's absence.

I certainly hope that we are not entering a phase with them where they play some sort of spoiler role, the official, speaking on condition of anonymity, told reporters on Clinton's plane. We are not proceeding with that assumption at all.

One bright spot at the conference may be the resumption of aid flowing into a World Bank trust fund for Afghanistan.

The United States and other donors stopped paying in to the trust fund when the International Monetary Fund suspended its programme with Kabul in June, but the IMF's decision to reverse course last month may pave the way to replenish the trust.

The conference is not expected to produce new aid pledges; instead, U.S. officials say they hope it will mark a start to a process outlining future support to be pledged by mid-2012.

Aid groups fear a precipitous drop-off of aid when troops go home could jeopardize what progress has been made to set up an effective state in one of the world's poorest countries.

Much more needs to be done to put Afghanistan on the road to recovery, stability and sustainable development, said Samuel Worthington, who heads InterAction, the largest alliance of U.S.-based international aid groups.

TALIBAN DECRIES FLAMES OF OCCUPATION

Rangeen Dadfar Spanta, Karzai's national security adviser, told reporters he wanted more aid effectiveness in both the civilian and security sectors.

Iran moved nearer centre stage in Bonn after it said it shot down a U.S. spy drone in its airspace and threatened to respond outside its borders to the alleged incursion.

International forces in Kabul said the drone may have been one lost last week while flying over western Afghanistan.

Iran has been accused in the past of providing low-level backing to the Taliban insurgency, and diplomats and analysts have suggested Tehran could ratchet up this support if it wanted to put serious pressure on U.S. forces in Afghanistan.

For its part the Taliban demanded in a November 30 statement an end to what it called foreign occupation of the country.

The conference was seeking to further ensnare Afghanistan into the flames of occupation and to turn it into a battleground and perpetual nightmare for the neighbouring countries.

(Additional reporting by Hamid Shalizi, Arshad Mohammed, Sabine Siebold, Myra MacDonald, William Maclean and Missy Ryan; Writing by William Maclean; Editing by Myra MacDonald)