The United Nations will be left holding another very dangerous baby state when international troops leave Afghanistan in 2014, many experts and diplomats believe.

President Barack Obama's warning at the NATO summit in Chicago that "there will be hard days ahead" reinforced the fears of many about Afghanistan after the US-led force -- which still numbers 130,000 -- has left.

The Western alliance has promised billions of dollars in aid for security forces and essential civilian services. The message from Obama and even UN leader Ban Ki-moon has been those in Afghanistan now are not going to abandon the country.

But critics say these will not make up for the international void as the President Hamid Karzai's government battles the Taliban and warlords for control of the country.

Even some of the Western countries are nervous. "It is not abandoning. But Afghanistan needs support and there are worries that the UN will be left carrying the baby -- and a very unstable one -- after 2014," said one senior Western envoy at the UN.

Thomas Ruttig, Kabul-based co-director of the Afghanistan Analysts Network, said there are "grave challenges and concerns about the viability of the transition strategy." NATO leaders in Chicago have "talked up" the reality.

"It is actually unfair to hand over the vast remaining problems to the UN, given that it had been virtually sidelined by NATO governments for the past years, and the central political role given to NATO itself."

Dipali Mukhopadhyay, a specialist on Afghanistan for Princeton University's Liechtenstein Institute on Self-Determination at Princeton, said the international community must be "cautious" about the expectations placed on the UN.

It has only a limited influence on domestic politics, Mukhopadhyay said. "In the face of foreign neglect and domestic violent conflict, its ability to build peace moving forward has always been limited."

She pointed out how the UN has already been a target of attacks in Afghanistan.

Jan Kubis, head of the UN Assistance Mission in Afghanistan (UNAMA), and a former foreign minister for Slovakia, said it was natural for the United Nations to take the lead role.

"The UN was created for this kind of situation," he told AFP in an interview in which he stressed how the United Nations was in Afghanistan well before the September 11, 2001 attacks that sparked the US-led invasion.

The UN envoy called the proposed military withdrawal "a positive development" for Afghanistan and the region as the troops provide "an artificial umbrella".

Some experts say Afghanistan, with its huge narcotics industry, a government accused of corruption and widespread unemployment, could easily veer back onto the path of becoming a failed state.

But Kubis said Western troops are not leaving "a country that is totally unstable, that has no chance to continue with a certain degree of stability."

The promised international aid will be crucial however.

About $4.1 billion will be needed each year to maintain Afghanistan's army and police over the next decade. The United States plans to give about $2.3 billion, Germany $191 million, Britain about $110 million and Australia $100 million.

A similar sum will be needed for new schools and hospitals and help for the government, Kubis estimated. Japan is organizing a donor conference in July to raise non-military finance.

Security and the government's relations with the Taliban will be the key to future peace.

Kubis says he expects NATO and Afghan forces to "create conditions that enable Afghanistan to maintain a major degree of security and stability for the overall majority of its population."

"I don't want to paint a rosy picture," he said. "I can speak equally strongly about challenges and problems" including the opium growing and millions of Afghan refugees in neighboring Pakistan and Iran.

"It doesn't mean that there will not be attacks, including suicide attacks," he said.

"It doesn't mean that all of a sudden Afghanistan will turn into a very stable, uneventful country that will fall from the map of the international community."

Government talks with the Taliban are currently suspended, but not definitively canceled and Kubis said they could succeed.

With the right international support, Afghanistan "has a fair chance to develop after 2014 in a way we would like to see it," Kubis said.