By Aaron Ross and David Lewis
KINSHASA/NAIROBI (Reuters) - When Democratic Republic of Congo's eastern neighbors took advantage of an outbreak of political turmoil there to invade in 1998, President Laurent Kabila turned to regional powerhouse Angola for help.
Angola's jets pounded Rwandan and Ugandan positions inside Congo and its troops patrolled the streets of the capital, Kinshasa, fearing the installation of a hostile government sympathetic to its own separatists.
This week, Laurent Kabila's son, Joseph, another Congolese president facing upheaval at home, heads to Luanda in search of a helping hand.
Heads of state at Wednesday's Congo-focused regional summit, many of whom have extended their own mandates at home, are likely to back a deal Kabila recently struck with part of the opposition to allow him to stay in power until at least April 2018, beyond his mandate which ends in December.
But analysts say this time Kabila cannot count on unalloyed support from Angola and other allies, especially if its leaders start to see Kabila as the problem, rather than the solution to difficulties in the central African giant.
"Angola prefers a Congo that is weak but stable," said Jason Stearns, director of the Congo Research Group at New York University.
"If the country becomes seriously unstable, Angola might begin to make its criticism of Kabila more public."
The main opposition bloc has denounced this month's accord as a pretext to allow Kabila to cling to power and maneuver to change the constitution – charges the government denies.
More than 50 people were killed last month in demonstrations against the extension of Kabila's term - which the government blames on the logistical problems of organizing a November election - and opposition leaders have vowed to give him a "red card" on Dec. 19, the last day of his term.
The goal of Kabila's trip to Luanda is to win support for the deal, under which a power-sharing government is to be named, his top diplomatic adviser, Barnabe Kikaya bin Karubi, said.
The government hopes regional recognition of the accord can help stem growing pressure from the United States and Europe on Kabila to stand down.
Even with that vote of confidence, further turmoil would damage Kabila's image as a guarantor of stability, one diplomat said. The United Nations fears large-scale violence could become "all but inevitable".
With direct Rwandan or Ugandan intervention in Congo now considered unlikely, Angola's main fear is an influx of refugees across its 2,600-km (1,600 mile) border if the political situation gets out of hand.
"I don't think they will want to see one person stay on if that leads to instability," the diplomat said of Angola.
Millions died in the 1998-2003 war that sucked in more than a half-dozen armies, including Zimbabwe and Namibia, which backed Laurent Kabila and then Joseph after his father's murder in 2001.
Since then, a series of foreign-backed insurrections has caused havoc in the east but without threatening Kabila's overall authority.
Kikaya said Kinshasa was not worried about weakening support from its allies but recent visits to Rwanda, Uganda and Tanzania suggest Kabila is working hard to shore up regional support.
"He still sees regional alliances as essential in his strategy to extend his time in office - but also possibly to secure personal guarantees in case he is forced out of power," said Vincent Rouget, Congo analyst at Control Risks.
Economic factors could also complicate Kabila's strategy. Relations between Congo and Angola have soured since 2013 due to a dispute over access to offshore oil concessions.
Likewise, South Africa could conclude that Kabila is no longer the best bet to protect its substantial economic interests in Congo.
Congo agreed in 2013 to sell more than half the power from its future 4,800 megawatt Inga 3 hydroelectric dam to South Africa but development has been sluggish and Congo is now almost certain to miss a 2020 deadline to begin providing electricity.
NOT ABOUT DEMOCRACY
The United States has already imposed targeted sanctions against members of Kabila's inner circle for allegedly violating human rights and blocking elections and the European Union is threatening to follow suit.
Such moves are unlikely to find support among Kabila's neighbors, especially Rwanda and Congo Republic, whose leaders recently pushed through changes to their constitutions to let them stand for third terms.
Instead, realpolitik and the desire for stability are almost certain to trump any idealism about democracy.
"African states don't want to set precedents about interference in domestic affairs," said Stephanie Wolters, an analyst at the Institute of Strategic Studies in Pretoria.
But the support of regional leaders will not be guaranteed forever and if he has any designs on staying around beyond April 2018, Kabila will need to find a much firmer legal basis for his position, the diplomat said.
"They found a legal way to stay on," the diplomat said. "Kabila hasn't."
(Writing by Aaron Ross; Editing by Ed Cropley and Giles Elgood)