Sudan and South Sudan have shelved their long-running conflict out of economic necessity. Both need to sell the region's oil that props up their economies.

But there are concerns that the peace pact between the countries, which waged a civil war almost continuously from 1955-2005, is likely to be temporary.

Under the agreement reached March 13, South Sudan's oil will be exported through pipelines running across its northern adversary, to the benefit of both.

But it's widely believed the deal will probably only last until South Sudan can find foreign investors to pay for a separate pipeline to the Indian Ocean through neighboring Kenya that cuts out the North.

Landlocked South Sudan hasn't been able to attract any takers but the emerging oil and natural gas boom in East Africa, from Uganda south to Mozambique, and maybe even South Africa, could eventually swing things its way.

Sudan's "dispute with South Sudan, particularly with regard to Abyei oil fields, will continue to threatens the Sudanese government," the U.S. global security consultancy Stratfor observed.

"Bilateral relations ... will remain unstable, as will the border, where rebel groups and state security forces continue to clash."

The Financial Times noted that the leaders of the two sides, President Omar al-Bashir of Sudan and President Salva Kiir of South Sudan, "face dissent from within their own regimes and coup rumors regularly circulate."

In November, Bashir's security services claimed to have uncovered a coup plot by senior military and intelligence officers, including former head of intelligence Salah Gosh. They're awaiting trial.

Even so, Bashir and Kiir held a historic April 12 meeting in Juba, the south's capital. It was Bashir's first visit to the southern city since South Sudan formally broke away from rule by Khartoum in July 2012.

Bashir, indicted for war crimes by the International Criminal Court four years ago, pledged the two countries would never return to war.

"I came to Juba because we now have the biggest chance to make peace," he declared standing beside Kiir in his signature black Stetson.

Oil has long been a key cause of conflict between the south, which is largely animist and Christian, and the north, predominantly Muslim and Arab.

Nearly all the oil lies in the south, much of it along the hotly contested and poorly defined border. Juba relies on oil for 98 percent of its revenues. But the only outlet is through northern pipelines to Port Sudan on the Red Sea.

Khartoum sought to impose massive transit fees to make up for its lost production and that triggered clashes between the two sides.

Juba shut production, running at 350,000 barrels per day, in early 2012 rather than pay the exorbitant transit fees, and both sides watched their economies disintegrate.

Inflation soared on both sides of the border. Both currencies crashed.

Both governments had to make massive budget and salary cuts, causing widespread hardship and discontent that were key factors in forcing them back to the negotiating table.

Now, officials say, production will resume and the first exports are expected to resume in late May.

Clearly, there are pressing economic reasons why it's not in the interests of either side to take any action that could re-ignite their conflict.

"South Sudan will try to maintain oil production, even if cross-border attacks and disagreements on other matters continued to occur, as is likely," Oxford Analytica observed.

But, it added, "both governments will remain dogmatic about their claims to disputed border areas.

"In the longer term, further disagreements between the two governments will likely impinge again on South Sudan's oil production and exports."

Both leaders have to contend with rebellious factions and protests, largely stemming from the economic difficulties of the last two years.

Bashir's grappling with armed conflicts in the Blue Nile, Darfur and South Kordofan regions, hangovers from the civil war.

There's widespread discontent in his army. Many officers see allowing the south to secede as a sign of weakness and there's considerable disquiet among middle-ranking and senior officers about where the country's going.

Bashir, a former army officer who took power in a 1989 coup, has said he won't stand for re-election in 2015 and there could be conflict over who will succeed him.