After years of relative peace, militants are again blowing up the pipelines that criss-cross the mangrove swamps of Nigeria’s Niger River delta, reducing oil output to the lowest in almost three decades and fueling a rally in global crude prices.

The resurgent conflict in Africa’s largest economy has a long history, interweaving corruption and poverty with regional rivalries and presidential politics, but at its core is money.

Between 2006 and 2009, when the oil-rich region was rocked by similar campaign of violence, the then president, Umaru Musa Yar’Adua, came up with a controversial solution: He offered a pardon and monthly stipends to fighters willing to disarm. After his death in 2010, former President Goodluck Jonathan doubled down on the strategy, awarding security contracts worth millions of dollars to rebel leaders, who went from blowing up pipelines to protecting them.

The opposition at the time denounced the deal, but it worked. Thousands of fighters accepted the presidential amnesty, joining new private security companies formed by their leaders and enjoying monthly payments from the government. The revolt, which at its worst point had sunk oil production by about a third to 1.65 MMbpd, quickly ended.

It hasn’t proved a long-term solution. President Muhammadu Buhari, a 73-year old former general elected last year on an anti-corruption platform, ended all pipeline security contracts and reduced the monthly stipends. In a wave of attacks this month, the militants responded by blowing up key pipelines, pushing oil output to a 27-year low of 1.4 MMbpd.

Brent crude oil, the leading international benchmark, has rallied as a result, reaching the highest since November on Wednesday. Prices slipped 2.5% to $47.69/bbl as of 4:34 p.m. London time Thursday.

The Nigerian military and the official in charge of the amnesty program didn’t respond to requests for comment.

The militants are trying “to arm-twist the new government to restore the pipeline deals,” said Dolapo Oni, a Lagos-based oil analyst at Ecobank Transnational Inc., one of Nigeria’s leading banks. “What it really is about right now is money.”

The new president, in contrast to Yar’Adua and Jonathan, is loathe to pay off the militants. Instead, he’s promised confrontation, vowing to “deal with them the way we dealt with Boko Haram,” a reference to a military onslaught against a seven-year Islamist insurgency that’s ravaged the country’s northeast.

“Buhari is willing to suffer the oil outages to crush the militants now,” said Helima Croft, the head of commodity strategy at RBC Capital Markets LLC, who followed the earlier wave of attacks as a West African analyst at the Central Intelligence Agency.

Even if he wanted to pay off the militants, the amnesty program and pipeline security contracts would be costly for Buhari. With oil below $50/bbl, Nigeria is hemorrhaging foreign exchange reserves and the economy is slowing sharply. After peaking at nearly $49 billion in mid-2013, dollar reserves have fallen to less than $27 billion, the lowest since 2005, according to official data.

Under Buhari, the annual budget for payments to ex-militants has been cut back from more than 60 billion naira ($300 million) to about 20 billion naira. In addition, Buhari canceled a pipeline security contract worth $103 million a year between the government and a Nigerian company called Global West Vessel Specialist Ltd.

“The predictable result is that this has driven militants back to the creeks,” said Malte Liewerscheidt, senior Africa analyst at security consultants Verisk Maplecroft.

Economic backdrop

While the rebels have shown themselves to be mainly motivated by money, the economic backdrop doesn’t help. The delta region accounts for the bulk of Nigeria’s oil and gas production and is home to its main export terminals. Sixty years after the first commercial oil discovery in the region, the area still suffers from acute deprivation, with youth unemployment as high as 40% and one of the worst rates of infant mortality in Nigeria.

The current wave of attacks is happening in the same area where Tompolo, a wanted man in Nigeria since February when he failed to show up in court to defend corruption charges, once operated.

The militants, which back in 2009 were loosely grouped around the so-called Movement for the Emancipation of the Niger Delta, now call themselves the Niger Delta Avengers. They claim to represent the people from the oil-rich region, portraying themselves as freedom fighters rather than rent seekers.

Avengers website

In a statement on a recently created website, the Avengers said they have nothing to do with older militants who have “been enjoying patronage from the government and royalty from multinational oil companies.”

The site’s authenticity couldn’t be verified by Bloomberg News, and the Avengers didn’t respond to requests for comment through email and Twitter.

For the oil companies, the situation now looks worse than during the last insurgency between 2006 and 2009.

The militants–perhaps building on the knowledge of their operations won through their security contracts–are striking firms including Royal Dutch Shell Plc, Eni SpA, Chevron Corp. where it really hurts: key oil-gathering hubs that knock down thousands of barrels of production at once as well as difficult-to-repair underwater pipelines.

The militants have this year destroyed pipelines feeding crude into Nigeria’s top export terminals, including Forcados, Bonny Light, Escravos and Brass River.

Risk averse

Compounding the problem, oil companies today are also more risk-averse than they were a decade ago. After the In Amenas attack in Algeria in 2013, when nearly 40 workers were killed, foreign oil companies err on the side of caution and evacuate their staff earlier. The Avengers have threatened to attack companies if they don’t stop pumping oil in two weeks, prompting Shell and others to airlift non-essential staff from vulnerable facilities.

The Nigerian government has promised to deal with the militants with a heavy hand. But the country’s security forces are busy dealing with separate attacks by the Boko Haram Islamist insurgency. Few believe the conflict can be resolved militarily.

“Sending large numbers of troops into the creeks isn’t likely to end the trouble, and if anything carries a risk of making a difficult situation worse,” said Daniel Magnowski, senior West Africa analyst at consultants Control Risks.