If you are lucky the troops manning the checkpoints will be sober.

If you are not, then you had better hope that your paperwork is in order, and the weapon slung over the shoulder of the soldier trying to squeeze another dollar out of you, is pointing away from your vehicle - especially as the gunman in question is probably just 15.

You would think that the peacekeepers of the United Nations Mission in the Democratic Republic of Congo (Monuc) would escape such challenges. But that is not always so.

In a UN convoy of nearly a dozen vehicles trying to move beyond Sake - a flashpoint during the fighting in September just beyond Goma - my car was plucked out, isolated, and turned around.

It was a move clearly designed to humiliate the UN, as much as ourselves.

Though it all came right in the end, it demonstrates the precarious relationship between the peacekeepers and government forces - troops, many of them once militiamen, rounded up like cats and fashioned into a regular army.

For the UN peacekeepers, the biggest success has undoubtedly been last year's elections.

But in the turbulent region of North Kivu, politics has delivered a terrible irony. Democracy has helped fan the flames of violence.

By-product of democracy

The political losses of the Congolese Rally for Democracy (RCD), the former Rwandan-backed rebels who prior to elections had control over much of the east, have helped to propel Tutsi rebel leader Laurent Nkunda to power.

He presents himself as a defender of the Tutsi minority - a position that not all Congolese Tutsi applaud, although nearly everyone you talk to has relatives in refugee camps across the border in Rwanda, and say anti-Tutsi sentiment in DR Congo is strong.

Gen Nkunda may be doing little to relieve this.

Monuc and the government in Kinshasa are criticised for being slow to see this by-product of the ballot box.

So there is now pressure to deal with all rebel groups simultaneously, including the Hutu Democratic Forces for the Liberation of Rwanda (FDLR), which the Congolese army has leant on for military support.

Gen Nkunda sees the FDLR as one of his principal enemies, and cites its presence as a key reason for his rebellion.

Mixed blessing

For ordinary Congolese, the presence of 4,500 UN forces in the east is a mixed blessing.

In Mugunga camp nestled between Goma and Sake, the overwhelming majority of people support Kinshasa's loudly trumpeted threats of an all-out strike against Gen Nkunda.

They view the peacekeepers as an impediment to that. The military tactic adopted by the UN in populated areas is to position its heavily armed troops as a buffer between Congolese forces and the rebels.

The aim is to minimise civilian casualties.

But those who have lost their homes during recent clashes around Sake are furious at what they see as obstructive intervention.

"When our Congolese soldiers are pushing Nkunda's troops, we see UN peacekeeping forces interrupt - why's that?" demanded one local resident.

Protection

The 17,000 UN peacekeepers operate under a mandate from Chapter VII of the UN Charter, which gives them liberty to protect civilians under imminent threat of violence.

That means shooting if necessary. But which civilians is Monuc prepared to protect?

In the camps near Rutshuru close to the border with Rwanda, there is frustration that the outlying villages are unprotected. Rapes in North Kivu, a favoured weapon of war, have doubled in the past month.

Murders continue unchecked and entire villages have been plundered.

Maj Gen Bikram Singh, the affable commander of UN peacekeepers there, is diplomatic in his response.

"It's a question of resources, troops cannot be deployed everywhere," he says.

"Troops are deployed in the context of impending operations and in the context of our mandate that is to protect civilians - they cannot be everywhere."

But although this is the biggest peacekeeping operation in the world, with a $1bn a year budget, troops are overstretched.

DR Congo is the size of western Europe. In many places roads are impassable and aid convoys face the threat of ambush.

Though humanitarian operators and human rights watchdogs agree the conditions are harsh, many are frustrated that Monuc's wings appear to be clipped.

Accused

The peacekeepers have revealed mass graves and intervened as warring sides have faced each other off, but Human Rights Watch says the peacekeepers have failed to expose rampant human rights abuses in North Kivu - the rapes, the murders, the recruitment of child soldiers that continue day by day.

The UN peacekeepers are stuck between a rock and a hard place.

They are mandated to support the Congolese Army (FARDC), but this a force that by broad consent is undisciplined and at times out of control.

The army has been implicated in gross human rights abuses.

Monuc's failure to speak out publicly on this is seen as a severe shortcoming and ill-judged.

Speak to the soldiers privately and there is a sense of confusion.

For many of the Indian peacekeepers around Sake it is their first peacekeeping mission. Many have fought in Kashmir with clear objectives and direct commands.

But this time it is different, and day by day there is a sense they are being dragged deeper into the chaos that is DR Congo.

There may be shortcomings, lapses in judgement and at times a sense of detachment from the people of Congo that the peacekeepers have been sent to protect.

But without their presence here would the situation be much worse? Almost certainly yes.