The U.N. envoy for Yemen warned that the risk of a return to fighting “is real,” urging warring parties to accept a longer extension of the current ceasefire due to expire next month.

Hans Grundberg’s stark warning late Tuesday came after he met in Saudi Arabia’s capital, Riyadh, with Rashad al-Alimi, head of the internationally recognized presidential council, and in Oman’s capital of Muscat with Mohammed Abdul-Salam, the chief negotiator of the Houthi rebels. He also met with Saudi and Omani officials to push for a cease-fire extension.

Grundberg, who was in Yemen’s capital of Sanaa on Wednesday for further talks with the Houthis, said in a statement he discussed a U.N. proposal to renew the truce for a longer time “to give Yemenis the opportunity to make progress on a wider basket of priorities.”

“We are at a crossroads where the risk of a return to war is real and I am urging the parties to choose an alternative that prioritizes the needs of the Yemeni people,” he said.

The efforts to renew the cease-fire have come as the two sides held military parades in territories under their control. The internationally recognized government held parades on the anniversary of 1962 uprising against the Imamate rule in northern Yemen.

The most notable parade was held by the Houthis last week in the capital of Sanaa, where they showcased a variety of weapons — including missiles and drones — which resemble those produced by Iran, their main backer in the war. The Houthi parades were a celebration of their seizure of the capital Sanaa in September 2014, which triggered the current civil war.

The U.N. envoy did not offer details on his proposal.

Nabil Jamel, a government negotiator, said the U.N. proposal includes ways to pay civilian servants in Houthi-held territories and reopen roads of blockaded cities, including Taiz. He did not elaborate.

Reopening the roads of Taiz and other provinces are part of the U.N.-brokered truce, which took effect in early April and was extended twice, the second time until Oct. 2. Both sides reported violations of the cease-fire. The truce established a partial reopening of Sanaa airport to commercial flights, and allowed fuel vessels in the port of Hodeida.

Abdul-Salam, the Houthi official in Oman, called for a permanent opening of the Sanaa airport and the Red Sea ports in Hodeida, along with payment of salaries and pensions, before engaging in political talks.

“There is no seriousness or credibility for any talk about peace in Yemen before the implementation of these urgent humanitarian issues,” he said on Twitter.

The truce has been the longest lull in fighting in Yemen’s war, now in its eighth year. Though both sides reported violations, the cease-fire has brought relief for Yemenis who have suffered from a decade of political turmoil and military conflict.

Aside from direct fighting, landmines and other explosive remnants continue to kill civilians in Hodeida. Earlier this week, the U.N. said at least 15 people, including children, were killed or wounded over the past week in the contested city, bringing the tally to over 100 dead, and 141 wounded since November.

Yemen’s brutal civil war began in 2014, when the Houthis seized Sanaa and much of northern Yemen and forced the government into exile. A Saudi-led coalition entered the war in early 2015 to try to restore the internationally recognized government to power.

The conflict has created one of the world’s worst humanitarian crises and over the years turned into a regional proxy war between Saudi Arabia and Iran. More than 150,000 people have been killed, including over 14,500 civilians.