Somalia’s two most powerful leaders were locked in a deepening standoff on Wednesday after they named different men to head the politically unstable Horn of Africa nation’s intelligence service.

The open row between President Mohamed Abdullahi Mohamed and Prime Minister Mohammed Hussein Roble, nominally over a murder investigation, marks an escalation of months of tension between them in a country already riven by militant attacks and clan rivalries.

It was triggered on Monday when Roble suspended Fahad Yasin, the director of the National Intelligence Service Agency (NISA), saying he had failed to deliver a report on the case of one of its agents who disappeared in June.

The suspension of the intelligence chief prompted a public rebuke from the president and highlighted growing divisions at the heart of the political elite.

The suspension – triggered by a dispute over investigations into an unsolved murder – followed months of wrangling that have threatened to further destabilize a country already riven by militant attacks and clan rivalries.

Prime Minister Mohammed Hussein Roble said he had told Fahad Yasin, the director of Somalia’s National Intelligence Service Agency (NISA), to step aside for failing to deliver a report on the murder of one of the agency’s agents.

Soon after, President Mohamed Abdullahi Mohamed issued his own statement calling the prime minister’s move unconstitutional. “(Yasin) should continue being the director of NISA,” the president said.

Somalia’s police chief called an emergency security meeting on Monday, officers told Reuters on condition of anonymity without going into further details.

“This shows the rift between the president and the prime minister is fully in the open – something that had been bubbling beneath the surface for some time,” Mahmood Omar, Somalia analyst at the International Crisis Group, told Reuters.

Roble appointed another man, Bashir Mohamed Jama, as interim head of NISA.

But the president late on Tuesday, named a third man, Yasin Abdullahi Mohamed, to head the agency.

The president’s appointee took over at a handover ceremony Wednesday morning, NISA said in a tweet.

Security around the agency’s headquarters was tight, local residents said.

The African Union, U.N., and foreign donor countries including Britain and the United States had on Tuesday called for a de-escalation of the row and advised the president and prime minister to “avoid any actions that could lead to violence.”

Roble and Mohamed had clashed in April, when the president unilaterally extended his four-year term by two years, prompting army factions loyal to each man to seize rival positions in the capital Mogadishu.

The confrontation was resolved when the president put Roble in charge of security and organizing delayed legislative and presidential elections.

That process was supposed to be concluded next month but several days ago was pushed back again.

In his late Tuesday statement, the president also named Yasin, the man Roble had sacked, as his personal security advisor.

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Also late on Tuesday, Roble accused Mohamed of “obstructing the effective investigation of Ikran Tahlil Farah’s case,” referring to the agent who went missing while working in the intelligence agency’s cybersecurity department.

Her family has said publicly they believe she was murdered, and that they hold the agency responsible.

The agency has not responded to the family’s allegation.