The UN's special envoy for Yemen has issued a warning to the warring factions in the state on the Arabian Peninsula. "Courage, personal sacrifice and perseverance" are needed to end the growing suffering of Yemen's civilian population, Ould Cheikh Ahmed said. Starting December 15 in Switzerland, Cheikh Ahmed wants to try to achieve a lasting truce.

According to the United Nations, more than 5,700 people have been killed in the conflict in the past nine months - nearly half of them civilians. Hundreds of thousands of people were forced to flee the fighting or are suffering because hardly any food or medicine is coming into Yemen. It seems unlikely that the overthrown government or the rebels will make concessions to one another. All previous mediation attempts have failed.

At least Cheikh Ahmed can hope that most of the important protagonists in the conflict will attend. The internationally recognized president is Abd Rabbo Mansur Hadi. However, he cannot rule from the capital, Sanaa. Houthi rebels expelled him and his government. From exile in Saudi Arabia, Hadi's team now has tried to get a foothold back in Yemen, at least in the southern port of Aden. The security situation there is bad. On Sunday, the governor of Aden was killed in an attack.

A third of Yemenites are Shiite

Hadi's main opponents are the Shiite Houthi rebels. The movement is named after its deceased founder, Badreddin al-Houthi. Yemen's Shiites, who belong to a different order than Shiite Muslims in Iran and Iraq do, make up one-third of the population. For decades they have struggled with the Sunni-dominated central government. Houthi fighters seized Aden back in January, but have since been repelled from the port city.

The Houthis are supported by Shiite fighters loyal to Hadi's predecessor, Ali Abdullah Saleh. The longtime ruler was forced to step down in 2012, following mass protests that allowed Hadi to assume power. Saleh and his dilapidated security forces are on the Houthis' side.

Representatives for Hadi, the Houthis and Saleh all plan to meet in Switzerland. But they are only some of the protagonists. If all parties involved in the conflict were to come together, UN mediators would need a long table. The power struggle in the southern end of the Red Sea has turned into a nationwide surrogate war. On Hadi's side there is a military alliance under the leadership of Saudi Arabia and eight other Arabic countries, including Egypt and most of the Gulf states. Last May, the West African state Senegal announced that it would join the alliance. The United States, France and Great Britain have provided logistical support.

On the opposing side, the Houthis can count on the support of Iran. Iran, though, has not been active in Yemen for a long time - certainly not to the extent it has been in Iraq, Syria and Lebanon, the Iranian journalist Saeid Jafari reported in the Middle Eastern online portal Al-Monitor. Nevertheless the close ties date back to the 1980s.

The continuing conflict in Yemen is seen as a proxy war between Sunni Saudi Arabia and Shiite Iran. Both states are struggling to gain dominance in the region and placing great emphasis on religious confession. However, the religious level is just one aspect of the war in a country with 26 million inhabitants - a side issue to the fighting. And the Sunni-dominated terror groups al Qaeda and "Islamic State" (IS) have tried to take advantage of the conflict, upping pressure on the exiled Sunni-led government and the Shiite Houthis alike.

A second Somalia?

Nations farther away have followed the developments with concern. Europe and the United States want to keep Yemen, the poorest Arab country, from breaking up completely. Leaders from Washington to Riyadh don't want a second Somalia. Saudi Arabia does not want a failed state on it southern border. A number of military installations and provincial towns are located within rocket range of Yemen.

Terrorists could profit heavily from the chaos and insecurity. Already, al Qaeda in the Arabian Peninsula has become one of the most dangerous branches of the international terror network. Last week, AQAP seized the southern cities of Jaar and Zinjibar. It only retreated from Jaar. For months IS has been trying to get a foothold in Yemen. With a series of attacks - including the assassination on the governor of Aden - IS is trying to push its rival al Qaeda from the region. The groups are struggling to gain the upper hand in Syria, Libya and other countries.

The escalating violence in the port city of Aden will lead to greater involvement by Saudi Arabia in Yemen, said Emily Estelle, from the Washington-based American Enterprise Institute thionk tank. That means no stability. "The proposed ceasefire will probably not hold," she said, "because both sides are still struggling for greater influence."