A United Nations translator holds a briefcase with listening equipment before a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, March 22, 2019. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario, attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario, attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario, attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita attends a news conference after a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, attends a news conference after a roundtable at the United Nations in Geneva, Switzerland, December 6, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Moroccan Foreign Minister Nasser Bourita, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Khatri Addouh, leader of the Sahrawi delegation and Frente Polisario, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Algerian Foreign Minister Abdelkader Messahel, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Mauritania's Foreign Minister Ismail Ould Cheikh Ahmed, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Mauritania's Foreign Minister Ismail Ould Cheikh Ahmed, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Horst Koehler, Personal Envoy of the Secretary General of the United Nations to the parties to the conflict in Western Sahara, arrives for a roundtable on Western Sahara at the United Nations in Geneva, Switzerland, December 5, 2018. REUTERS/Denis Balibouse

Map of Western Sahara showing Polisario territory, and location of Guerguerat

Mohamed al Wali, 65, a Polisario fighter, stands next to a Sahrawi Arab Democratic Republic flag at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

The Polisario Front soldiers drive a pick-up truck mounted with an anti-aircraft weapon during sunset in Bir Lahlou, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Polisario Front soldiers stand at an entrance of the fifth sector base in Bir Lahlou, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Moroccan soldiers are seen on an earth wall that separates areas controlled by Morocco and the Polisario Front in Western Sahara, September 10, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Barra Mebarak, 22, a fighter who joined the Polisario forces in 2012, is seen at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Second sector commander Sidi Waghal (3rd L) speaks to his officers at the forces base on the outskirts of Tifariti, in Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A Moroccan tank which was downed by the Polisario Front during their battles with Morocco's army is seen in Tifariti, Western Sahara, September 9, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Sidi Ahmed Brahim, 25, a fighter who joined the Polisario forces last year, speaks to Reuters journalists at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A rocket is pictured near an earth wall that separates areas controlled by Morocco and the Polisario Front in Western Sahara, September 10, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Moroccan soldiers are seen on an earth wall that separates areas controlled by Morocco and the Polisario Front in Western Sahara, September 10, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A helicopter belonging to the Minurso (U.N. mission in Western Sahara) flies over the Polisario second sector forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

The Polisario Front officer prays at the grave of the late Western Sahara's Polisario Front President Mohammed Abdelaziz in Bir Lahlou, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY

Hamuya Khalil, 49, a Polisario fighter, stands in an armored vehicle at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

An indiginous Sahrawi woman sits inside her tent in Tifariti, Western Sahara, September 8, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY

Mohamed Maloud Ahmed Bakita, 86, a former Western Sahara Polisario soldier, sits inside his family tent as he talks with Reuters journalists about the battle where he lost an eye fighting Moroccan troops more than two decades ago in Tifariti, Western Sahara, September 8, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

An indigenous Sahrawi man walks outside the only hospital in Tifariti, Western Sahara, September 8, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A 5-day-old western Sahrawi child is seen at the only hospital in Tifariti, Western Sahara, September 8, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Indigenous Sahrawi people sit on a pick-up truck as they drive towards Tifariti, Western Sahara, September 8, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Sidi Brahim Mohamed Embarek talks to Reuters journalists as he stands beside the wreckage of a Moroccan air force F-5, which was shot down by the Polisario in a 1991 battle in the Western Sahara war, in Tifariti, September 9, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY

Saleh Sidi Ahmed, 56, a soldier with the Western Sahara Polisario forces, walks near the ruins of a house bombed by the disputed region war with Morocco more than 25 years ago in Tifariti, Western Sahara, September 8, 2016. REUTERS/ Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A tent belonging to an indigenous Sahrawi family stands in Tifariti, Western Sahara, September 8, 2016. REUTERS/Zohra Bensemra SEARCH “POLISARIO” FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.