In 2001, I was in a bar in Kigoma, on the Tanzanian side of Lake Tanganyika. As I sipped my beer, I could hear the clipped tones of a South African speaking into a radio transceiver. He was ordering supplies for the United Nations peacekeeping mission known as Monuc, then operating out of Kalemie on the lake's Congolese side. At the time, Monuc's blue berets were just about managing to keep a lid on things in eastern Congo, but already the strain was showing.

Earlier that year Congolese president Laurent Kabila was shot by his bodyguard. He was replaced by his son Joseph, largely as a result of pressure brought to bear by Robert Mugabe. Zimbabwe was one of a number of nations then taking part in the second Congo war (1998-2003). It was allying itself, along with Angola, Namibia, Chad and Sudan, with the Kabilas. On the other side, though sometimes fighting each other, were Uganda and Rwanda.

All sides in this many-phased conflict, which has claimed more than five million lives during the past decade, have been engaged in extraction of Congo's rich mineral deposits. These have been a cause of bloodshed in the region right back to the 1960s, following Belgium's messy exit from its former colony. These riches are one reason why regional collaborations to end the conflict have so far failed; another is the historical effects of the 1994 Rwandan genocide.

Since the official end of the second Congo war, fighting has been concentrated in the eastern region - the Congolese borders of Uganda, Rwanda and Sudan - with mainly Rwandan proxies fighting a circumstantial alliance of the Congolese army and Hutus. The most recent focus is on the territorial ambitions of "General" Nkunda, a Rwandan-backed warlord accused of massacring 150 civilians in Kivu last month.

Last week Ban Ki-moon, the UN secretary general, wrote to European leaders asking the EU to intervene in Congo. The recent collapse of the Congolese army in the eastern region has caused hundreds of thousands of people to be displaced and an eruption of mass killings and rapes. The letter was an admission that Monuc had failed, having too few troops to deal with a conflict that could potentially again spread over an area as large as the EU itself.

The UN has authorised more troops, but they will not be deployed for at least four months. EU foreign policy chief Javier Solana, who met Ban yesterday in New York, has proposed four options to EU leaders: sending a rapid response "battle group" of 1,500 troops; dispatching within several months a 3,000-strong mission; simply reinforcing Monuc with forces from European countries; or achieving a concrete objective, such as securing the all-important Goma airport and other sites.

The second proposal has already been rejected by France. On Friday, Nicolas Sarkozy said African forces should reinforce Monuc. He also questioned whether an increase in the number of troops was the answer. Britain, too, is adamant the EU should not get involved, and Germany is not keen. These big EU players cite practical or tactical reasons, but underneath the shilly-shallying is a collective failure of moral leadership. The long-term lack of proper response to the scale of this fluid, deadly conflict is part of the same narrative that saw western governments fail to respond to genocide in Rwanda. It is eminently possible that a tragedy of a larger scale could now take place.

Ordinary Africans are already suffering on a scale that dwarfs casualties from terrorist outrages and conflicts in Afghanistan and Iraq. In particular, the harrowing reports of mass rape in the Congo demand a response - a military one. There are good political as well as human rights reasons why stopping mass rape should be the platform for this intervention. Women are the "glue" in central African society. They are the carers, the food providers. If many in several generations of women are damaged, injured or killed, the chances of a return to civil society are extremely slim.

In the immediate term, pressure should be put on the Rwandan leadership itself to rein in Nkunda; in the short term, Monuc should be supplemented by a large EU force; in the longer term, as eastern Congo seems ungovernable from Kinshasa, I see no option but the creation of a buffer state on the western shores of Lakes Kivu and Tanganyika. This could be achieved by regional forces with Monuc-EU backup.

Geopolitically, the Great Lakes region is a hornet's nest - but unless someone puts smoke in that nest, the world could soon be living with a greater shame than the Rwandan genocide.

• Giles Foden is the author of The Last King of Scotland and professor of creative writing at the University of East Anglia g.foden@uea.ac.uk