Armed clashes between Morocco and the Polisario Front reflect the movement's frustration with a three-decade status quo that has frozen its dreams of independence in the Western Sahara, analysts say.
The group, backed by Morocco's arch-rival Algeria, has long demanded a referendum on independence in the territory as provided for by a 1991 UN Security Council resolution.
Morocco has offered autonomy but insists it will keep sovereignty over the former Spanish colony.
But after a 1991 ceasefire deal crumbled earlier this month "taking up arms again is a question of survival for Sahrawis", said Algerian political analyst Mansour Kedidir.
Morocco in early November accused the Polisario of blocking a key highway for trade with the rest of Africa, and launched a military operation to reopen it.
The pro-independence movement, which says the road was built in violation of the 1991 deal, declared the truce null and void and insisted it had no choice but "to intensify the fight for national liberation".
It has since announced daily attacks, mostly targeting a Moroccan defensive wall in the territory.
Under the 1991 truce deal, Morocco controls around three-quarters of the Western Sahara, including its considerable phosphate deposits and access to its rich Atlantic fisheries.
The Polisario controls the rest of the territory, which in total is around half the size of Spain.
Talks between Morocco and the Polisario, as well as neighbouring Algeria and Mauritania, have been suspended since March 2019.
The UN's envoy for the territory, former German president Horst Kohler, quit in May of that year citing poor health and has not been replaced.
The Polisario is now "desperate", said a western diplomat, on condition of anonymity given the sensitivity of the issue.
"They see that there is no political track and they just want to get some attention, so some pressure (is) made on a political solution," he said.
Kedidir said the Polisario's frustration was understandable given the UN's "inability to settle the issue", and the movement says the coastal highway linking Morocco to Mauritania was built in violation of the ceasefire.
Meanwhile Morocco accuses the Polisario of "provocations" in the Guerguerat buffer zone.
Another diplomatic source said civilian protesters at the buffer zone had been "supported by four all-terrain vehicles equipped with machine guns", which entered the area via Mauritania.
That prompted Rabat to "solve the problem definitively with massive force", sending in troops supported by some 200 vehicles, he said.
The UN has warned of the dangers of a collapse of the 1991 ceasefire, signed after 15 years of bitter conflict.
But despite the 1991 Security Council resolution calling for "a referendum for self-determination of the people of the Western Sahara", Morocco points out that the most recent resolution makes no mention of a vote.
The Polisario has vowed to continue its struggle for a referendum.
'Freedom or death'
Algerian former diplomat Abdelaziz Rahabi said Sahrawis were right "not to give much credit to the UN", saying the world body's Western Sahara mission MINURSO had been reduced to the role of "traffic police".
"The Security Council is being held hostage by France, and to a lesser degree by the United States, which does not envisage any other solution than the authority of Morocco over Western Sahara," he said.
"The status quo... hurts the interests of the Sahrawi people and threatens stability in the region."
The first Western diplomat warned of the consequences of the Polisario's leadership becoming weakened.
"We have to do something because the problem will not go away," said one of the western diplomats.
"I am afraid that the leadership of the Polisario will weaken. The young people don't have this patience, they could become much more radical and we don't want that."
The Polisario Front has said it is mobilising "thousands of volunteers" to join its fighters, and in refugee camps in Algeria, frustrated young Sahrawis say they are ready to take up arms.
"The Sahrawi people has given enough time for peace," said Mohamed Ambeirik, 28.
A graduate in international relations, he has decided to join the Polisario in its armed struggle.
"We will continue with what our elders started. We're sick of waiting," he said by phone from a Polisario camp in Tindouf.
"Without a country, we're nothing. Today, it's freedom or death."