The Big Question: Why has the crisis grown worse in Darfur, and can there be a solution?

Why are we asking this question now?

Sudan has told the African Union (AU) force overseeing the peace agreement in Darfur that it must leave the region by the end of the month. The UN Security Council passed a resolution last week that would send 17,000 peacekeepers to Darfur to replace the AU troops. But the Sudanese government has rejected the UN's plan, likening it to "western colonisation".

Without agreement from Khartoum, the UN is unable to deploy any peacekeepers. Instead, Sudan plans to send more than 10,000 troops to Darfur. Human rights groups have accused Sudan of in effect sending the same soldiers who displaced Darfur's refugees to protect them. Over the past week, there has been a military build-up in the region, with witnesses reporting an influx of Sudanese military equipment and troops.

What is behind the problems in Darfur?

Militants from several non-Arab African tribes in Darfur, in particular the Fur and Zaghawa, started a rebellion against the Arab-led Sudanese government in 2003 claiming discrimination and a lack of resources in the region. The government used a local militia, known as Janjaweed, to crush the insurgency. The Janjaweed, with the support of Khartoum, targeted civilians of the same ethnicity as the rebel groups. More than 85,000 people have since been killed, a further 200,000 have died from war-related diseases, and more than two million have been displaced.

Negotiations in May, led by the US and by Britain's International Development Secretary, Hilary Benn, created the Darfur Peace Agreement, which was signed by the Sudanese government and one of the rebel groups - a faction of the Sudan Liberation Army (SLA) led by Minni Minnawi. The other SLA faction and the Justice and Equality Movement (JEM) refused to sign it. The groups opposed to the agreement have since merged into the National Redemption Front (NRF).

Why are the war tactics so cruel?

Sudan's president, Omar al-Bashir, came to power via an Islamist-backed coup in 1989. The regime's main tactic of repression, practiced during the long civil war in the south, as well as in Darfur, is to arm local militia and provide them with the military and logistics support they need to wipe out rebellions. In Darfur, much of the ethnic cleansing has been carried out by the Janjaweed, Arab militia on horseback. The main rebel groups have also been accused of committing war crimes. Since the peace agreement was signed in May, Minnawi's faction of the SLA has carried out attacks alongside government forces against those rebels who were against the agreement.

Is it genocide?

The 1948 Genocide Convention defines genocide as "acts committed with intent to destroy, in whole or in part, a national, ethnic, racial or religious group, as such". The United States has referred to the crisis in Darfur as "genocide", but the United Nations has gone no further than the terms "crimes against humanity" and "war crimes".

The Aegis Trust, Britain's leading genocide prevention organisation, said that the Government of Sudan's actions now constitute genocide. They warned that "the genocide now faced could be on the scale of that in Rwanda in 1994".

The semantics are important. The Genocide Convention imperils countries to act to prevent genocide when it occurs. During the Rwandan genocide, the US Secretary of State Warren Christopher would only say that "acts of genocide" had been committed. Had he called it genocide, the US would have been bound by the 1948 convention to act.

Who supports the Sudanese government?

Three countries abstained on last week's UN resolution - China, Russia and Qatar. The abstentions indicated the types of support Sudan can rely on. Qatar, the only Arab nation currently sitting on the UN Security Council, did not wish to be seen supporting an international force entering another Arab country. The Arab League asked the UN to postpone the vote and refused to send their observers to the Security Council session.

For Russia and China, the motives are economic. Both have close economic ties with al-Bashir's regime, in particular China which has big oil interests in the country. There is another crucial pillar of support which Khartoum can lean on. Osama bin Laden has backed al-Bashir's decision to refuse a UN presence in Darfur, and al-Bashir has in turn borrowed rhetoric from al-Qa'ida's leader, likening any UN force to "western colonisation".

Why did the recent peace agreement break down?

There are three principal reasons. Firstly, and most importantly, most of the rebels did not sign it. Secondly, the African Union force sent in to police it has never been given enough resources to do the job properly. Just 7,000 soldiers have been patrolling a region the size of France. The lack of manpower has caused huge problems. For example, under the agreement the AU was supposed to provide protection to women leaving camps to collect firewood. As the force became stretched, these patrols were not carried out, meaning women were left vulnerable to attack and many were raped.Thirdly, some human rights groups argue that the Sudanese government never wanted the agreement to work. There have been numerous violations of the agreement, most recently on 28 August when the area of Kulkul, some 40 km north-west of North Darfur's capital al-Fasher, was heavily bombed, prompting civilians to flee the town and their villages.

Is there any hope of a solution?

The African Union will try to persuade Sudan to allow their forces to stay. And diplomatic pressure from fellow African nations, particularly Sudan's neighbours, may encourage Khartoum to change its mind.

Western diplomats are beginning to talk privately about introducing economic sanctions against Sudan's leaders. Many senior government figures have rich oil interests. Regional analysts believe this is the best way of forcing Khartoum's hand.

Should the outside world intervene by force if the situation worsens?

Yes...

* The genocide in Rwanda showed just how bad things can get if local rivalries are allowed to issue in organised killing

* There is not much point in having an international convention on genocide if no one enforces it

* The implications of allowing another genocide to take place in Africa could lead to a complete collapse in the UN's authority

No...

* Only the United States and Nato have the power to enforce a military solution, and they would be seen as western imperialists

* The recent examples of Iraq and Afghanistan show how much easier it is to overthrow a government than to ensure order afterwards

* As bad as Darfur could become if left alone, outside intervention might well make matters even worse